2006 A4 2.0tdi BRE Cam Sensor Problem

Hello

I hope someone can help. My car was cranking over a lot before starting, VCDS diagnosed intermittent cam sensor.
Bought a new one from Audi dealer as did not want to risk an eBay item, fitted it today, what a so and so!! Car won't start at all.
No fault codes on VCDS. Measured resistance of new sensor and its short circuit between 12v(pin1) and output(pin2). Measured voltages on ECU side of cam sensor plug.
Pin 1 5v, should be 12v. Pin 2 5v correct and pin 3 earth, correct.

Your advice please as I am concerned that the ECU has been damaged?

This may appear my 1st post but I've been a member for years but could not remember login details accurately enough, so rejoined..

Thank you for help.

John.

The ecu may have dropped the voltage to 5V as a safety measure while you were testing/ unplugged. I wouldn't worry too much until you know how to test the outputs accurately. Just a suggestion, not a criticism!

I can't double check at home but those sensors are often 5v. Could you private message me your reg number and post the part number of the sensor you fitted?

Crasher. Thank you for your offer of help. I gave up trying to sort it and called out RAC. He diagnosed a stuck EGR valve by putting his hand over air inlet, there was no suck when cranking. Thevoltages and in particular the resistance readings I found on another forum were way out and led me down the wrong path. I don’t understand the stuck EGR valve logic but it’s now starting and running. If the throttle valve was stuck shut, it would make sense but apparently it wasn’t.

Those electric EGR valves can be trouble but so can the manifold flap V157 which is the unit in front of the EGR valve, these can stick shut which will prevent the engine starting.