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Discussion Starter #1
Check engine light came on. Problem: Bank 1, Sensor A. Crankcase Position Sensor.

Question: where on the engine is the above sensor? Car runs just fine. What does the sensor do? Will it cause damage if I don’t change it?
 

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Where it is will depend on which engine you have. Easiest is likely to stick "crankshaft position sensor" and your engine code (three letters, on various stickers on the car) into your favourite search engine.

The position sensor sends information to the engine management system about the rotation of the crankshaft, which allows it to manage fuel injection and timing. Without that signal, the engine management system can't do its job and the car will be operating in a failure mode, which likely means worse fuel efficiency and poorer acceleration. If not replaced, you may get further issues and the car could even refuse to start. The part costs around 20 $/€.
 

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The crank position sensor is the most critical electronic component of a modern ECU car. The ECU will only start its program to run your engine if it gets a good signal from the crank sensor. Since your car has not entered the 'Won't start or run' mode and you only have the MIL warning, I suspect the sensor or wiring could be intermittent? Because it is such a critical engine sensor, they are usually very reliable. Diagnostics results sometimes mean more than one thing. E.g the crank sensor digital code output is used for other functions which might show as a fault there, but not be the critical fault stopping the car ECU running. If your car is starting and running o.k other than the MIL light, I would suspect signal glitches, intermittent operation, or another part of the engine management using the signal not liking what it gets. :confused: Is your battery good?
 

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Discussion Starter #4
Looks like the sensor is not that difficult to change but my question is will a have a no start situation without relearning the new sensor? Does a new sensor require relearning?
 

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Looks like the sensor is not that difficult to change but my question is will a have a no start situation without relearning the new sensor? Does a new sensor require relearning?
The sensor doesn't need to be relearned but you will need to clear the fault after installation of the new sensor.

Mick
 
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