what are the symptoms of a bad crankshaft position sensor?
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1990 Audi 90 Question: crankshaft position sensor
Answer #1J4242 from Precision Auto Repair & Sales Inc, November 22, 2010, 10:10Technician
A few of the most well known symptoms will jump right out at you. First being that the vehicle will not start. It will crank, but it will not fire if the sensors aren't reading. Second is that your Check Engine Light will be on. When I diagnose these I watch the datastream to see what my signal is from the cam and crank sensors. Depending on which is not reading, I'll make sure the wiring is ok, then I remove the sensor and look in the hole to make sure that the tone ring that the sensor reads isn't damaged in any way. Then I will bench test the sensor. It's just a magnet so it's a simple test looking for resistance to be within spec. Then I will condemn accordingly. It's actually fairly common for the crank sensor to be faulty in your vehicle. Best of luck!