davedeez

Hey, I'm new to Audi, I just bought a 2004 s4 4.2l. I'm having a problem revving the engine to red line. The code in the ecu is po321 engine rpm sensor. I changed the sensor, cleared the code and it's back. Then I checked the wiring all is good. Cleared it again and it's back po 321. Anyone have any thoughts on this? Could I have a junk new sensor? I got it from AutoZone.

DOALLAR

Well congrats on your purchase! The reference p code is indeed your engine speed (rpm) sensor. The speed sensor correlates with your cam position sensors. Which tells the ECU engine and cam speed. I would check the cam postion sensors in/on driver and passenger banks - to rule 'em out. Also, Im not sure what brand speed sensor "AutoZone" carries but In any situtation dealing with sensors I purchase OEM stock. Good luck!

davedeez

Thanks. So far I love the car besides the minor issue. The data from the scanner show the other sensor are working as they should. The crank sensor however signal is intermittent. Maybe I'll try another sensor. It's annoying to try to spin the rpms up and it feels like I'm hitting a rev limiter from 4.5k to 5.5k, then sometimes it doesn't.