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Imagine spending hundreds of dollars on
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new parts that your car still feels
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slow, shakes at red lights, and burns
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Well, I have a secret that most repair
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shops do not want you to know.
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The real reason your car is losing power
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usually has nothing to do with broken
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parts. Instead, there is a tiny hidden
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piece inside your engine secretly
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stealing your horsepower right now.
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Mechanics hide this trick because fixing
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it takes 5 minutes and costs almost
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Today, I am going to show you exactly
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what this silent killer is and how
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finding it will bring your engine back
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Mechanics see this exact situation every
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single day. A frustrated car owner comes
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into the shop with a vehicle that is
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running terribly. They have already
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spent a fortune putting in new spark
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plugs, new ignition coils, and even a
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brand new fuel pump, but the car still
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drives poorly. The truth is, your car is
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losing power because of a thin layer of
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dirt, oil, or corrosion sitting on a
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hidden sensor. These little electronic
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parts are the eyes and ears of your
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engine's computer. When they get dirty,
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they lie to the computer and the
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computer makes a mess of your engine. We
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are going to break down the worst
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offenders, [music] starting from number
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eight, and working our way down to the
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ultimate most ignored secret at number
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Number eight is the mass airflow sensor.
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This is one of the most important parts
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of your car, yet it is almost always
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ignored. Its only job is to measure
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exactly how much air is being sucked
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into the engine. To do this, it uses a
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tiny heated wire that is almost as thin
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as a single piece of human hair.
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As air blows past this heated wire, it
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The computer measures how much
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electrical current is needed to keep
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that wire hot and uses that data to
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calculate the airflow. The nightmare
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starts when microscopic dust particles,
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oil vapor from the engine block, and
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general city pollution slip past your
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air filter and stick [music] to that
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delicate little wire. The dirt acts like
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a tiny blanket. Suddenly, the wire
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doesn't cool down like it should and the
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computer gets totally inaccurate
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>> You will feel a noticeable loss of power
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when you try to accelerate hard. Your
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gas mileage will drop. Your engine idle
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will become rough and bouncy, and
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sometimes the car will even stall when
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Many cars will throw a rich or lean
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engine code, making you think you have a
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But in reality, you just need a can of
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mass airflow sensor cleaner. You
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carefully spray the wire without ever
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touching it with your hands or a tool,
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and the problem vanishes. Number seven
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is the manifold absolute pressure
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sensor. Not all cars have a mass airflow
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sensor. Many use this pressure sensor
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instead. Rather than directly measuring
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the air, it measures the vacuum pressure
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inside your engine's intake. It uses a
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very sensitive internal element that
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changes its electrical resistance as the
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engine vacuum changes.
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When your foot is off the gas pedal, the
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When you floor the gas pedal, the vacuum
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drops. The problem rarely lies inside
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the sensor itself. The trouble usually
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starts with the little rubber vacuum
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hoses connected [music] to it. Over the
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years, engine heat bakes these hoses
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until they get hard, brittle, and crack.
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Even the smallest pinhole leak will
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completely destroy the vacuum reading.
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The sensor will tell the computer that
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the engine is under a heavy load even
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when you are just sitting at a stop
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sign. The computer reacts by dumping
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extra fuel into the engine. Your exhaust
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will start blowing black smoke, you will
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waste a ton of gas, and your engine will
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run terribly rich. Cleaning the sensor
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port and replacing a cheap piece of
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cracked rubber hose fixes the majority
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of problems blamed on this sensor.
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Number six is the oxygen sensor. This
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sensor lives a terrible life inside your
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blazing hot exhaust pipe. It has the
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very important job of smelling your
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exhaust gases to see how well the engine
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is burning fuel. It operates using a
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ceramic element that gets heated to
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extreme temperatures. It generates a
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small electrical voltage depending on
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how much oxygen is left in the exhaust.
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The engine computer uses this real-time
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voltage to perfectly balance the fuel
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injectors thousands of times every
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minute. Because it lives in the exhaust,
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it [music] gets attacked by everything.
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If you use poor quality fuel or if your
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engine burns a little bit of oil because
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of worn piston rings, the tip of the
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oxygen sensor gets coated in heavy
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carbon soot and chemical residues. This
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poisons the sensor. It becomes lazy and
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stops sending fast, sharp signals to the
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computer. When this happens, the
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computer defaults to a safe mode, which
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means it sprays extra fuel just [music]
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to be safe. You lose horsepower, your
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gas mileage tanks, and you will almost
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certainly fail your state emissions
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Number five is the throttle position
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sensor. Imagine a volume knob on an old
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radio. Sometimes when you turn the knob,
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the sound gets scratchy and cuts out in
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certain spots. The throttle position
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sensor works exactly the same way. It is
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bolted right to your throttle body and
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tells the computer exactly how far you
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are pressing the gas pedal.
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It has a tiny wiper arm inside that
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sweeps across a [music] track. If that
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internal track gets dirty or worn out
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from years of driving, it develops dead
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These dead spots almost always happen
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right at the pedal positions you use the
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most, like cruising at highway speeds or
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lightly pressing the gas in slow
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When the sensor hits a dead spot, the
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computer briefly loses track of your
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You will feel a very annoying
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The car might jerk forward suddenly, or
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you might completely lose power for a
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[music] split second. Mechanics test
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this by slowly pressing the pedal and
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looking for sudden drops in the signal
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voltage. Number four is the crankshaft
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position sensor. Without this part, your
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modern engine is completely blind. It is
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usually bolted down near the bottom of
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the engine, right next to the spinning
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crankshaft. Its job is to read a toothed
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metal wheel as it spins by. By counting
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these teeth, the sensor tells the
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computer the exact position of the
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engine internals, so the computer knows
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exactly when to fire the spark plugs and
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fuel injectors. This sensor is highly
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magnetic and because it sits at the
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bottom of the engine, it acts like a
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magnet for trouble. Over thousands of
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miles, it attracts tiny metal shavings
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from normal engine wear. It also gets
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coated in leaking oil and road grime.
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Eventually, a thick metallic sludge
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covers the tip of the sensor and the
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magnetic signal gets blurry. When the
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computer cannot clearly read the teeth
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on the wheel, you get random engine
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misfires. Sometimes the car will just
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crank and crank without starting. Other
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times, the engine will completely shut
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off out of nowhere while you are driving
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Pulling this sensor out and wiping the
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magnetic tip [music] perfectly clean is
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a simple fix that saves a massive amount
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of frustration. Number three is the
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engine coolant temperature sensor. This
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is basically the thermometer for your
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car. It sits directly in the engine
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coolant and tells the computer if the
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engine is freezing cold from sitting
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overnight or blazing hot from driving.
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This temperature [music] reading changes
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everything. When the engine is cold, the
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computer commands a richer fuel mixture
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to help the car start smoothly and it
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raises the engine idle speed to warm
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things up. But here is where things go
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wrong. It is rarely the thermometer tip
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in the coolant that fails. The problem
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happens at the electrical connector on
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top. Over time, heat and moisture cause
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green corrosion to build up on the metal
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pins. This corrosion creates resistance
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in the wire. The computer gets confused
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and starts thinking the engine is
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constantly minus 40° even when it is
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hot. It will dump massive amounts of
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fuel into the engine, ruining your gas
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mileage. On [music] the flip side, the
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bad connection might trick the computer
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into thinking the engine is overheating
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when it isn't, causing the cooling fans
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to run at maximum speed for absolutely
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no reason. Fixing this requires
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unplugging the sensor and cleaning the
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metal pins perfectly rather than
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draining your coolant to replace the
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whole part. Number two is the intake air
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temperature sensor. Just like the
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coolant sensor, this measures
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temperature, but it measures the air
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getting sucked into the engine. Cold air
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is very dense and needs more fuel to
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burn properly. Hot air is thin and needs
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less fuel. The sensor tip is usually
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made of a tiny exposed piece of material
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Because it [snorts] sits in the air
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intake, it gets blasted with oily
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blow-by gases and fine dust. Once it
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gets coated in a layer of grime, it
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cannot feel the air temperature changing
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accurately. Your car will start
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suffering from very strange,
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inconsistent performance. It might run
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perfectly on a Tuesday, but drive
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terribly on a Wednesday. You might have
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horrible cold starts followed by weird
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power drops when you merge onto the
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highway. This sensor is incredibly
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fragile. You cannot scrub it with a
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brush or wipe it with a rag. You can
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only spray it gently with electronic
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contact cleaner and let it air dry. If
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you bend the tip even slightly, it is
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ruined forever. [music]
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And finally, number one. This is the
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biggest secret in the automotive repair
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world. Cleaning [snorts] your electrical
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terminals and connectors. You can buy
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the most expensive, high-quality
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replacement sensors on the market, but
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if the wiring connection plugging into
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that sensor is dirty, your car will
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The wiring harness in your car is like
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the nervous system of a human body.
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Every single sensor we just talked about
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connects to the main computer through
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plastic plugs with tiny metal pins
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inside. Because engines vibrate
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violently, get washed with water from
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the road, and bake in extreme heat,
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those connections degrade.
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Moisture gets past the rubber weather
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The metal pins oxidize, turning dark
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gray or crusty green. [music]
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When a mechanic gets a car with
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mysterious ghost problems that make no
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sense, the first thing they [music] do
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is start unplugging sensors. You take
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electronic contact cleaner and spray
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both the male and female sides of the
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plug. Let the dirt wash out. Let it dry
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completely. Before you snap it back
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together, you apply a tiny dab of
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dielectric grease around the rubber seal
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of the plug. This grease seals out water
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and locks out oxygen so the corrosion
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never comes back. Spending a weekend
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pulling apart your engine connections,
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cleaning them, and snapping them firmly
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back into place will solve more engine
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hesitation and stalling problems than
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replacing parts ever will. It takes
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patience, but it completely restores the
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electrical health of your vehicle.
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Taking care of your car is about so much
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more than just putting in fresh oil and
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changing the brakes. If you take the
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time to clean these tiny electronic
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pieces, your engine will reward you with
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smooth power and great fuel economy for
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years to come. If you found this video
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helpful and want to learn more simple
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ways to save thousands of dollars on
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your car, please hit that like button
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right now. It means the world to me and
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helps out a lot. [music] Make sure you
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subscribe so you never miss another tip.
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Thank you so much for watching Car
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Throttle, and I will see you in the next
