1998 VW Passat with 1.8l 92kW engine (without turbo) has about twice the fuel consumption it should have and throws this error message
VAG-COM Version: Release 311.2-N
Control Module Part Number: 8D0 907 558 S
Component and/or Version: 1,8L R4/5V MOTR AT D01
Software Coding: 04031
Work Shop Code: WSC 05314
1 Fault Found:
00515 - Camshaft Position (Hall) Sensor (G40)
29-00 - Short to Ground
The problem is that it is not true. I measured the signal from terminal no. 2 of the sensor plug with an oscilloscope while the engine was running and it looked OK - nice rectangular pulses between 0 and 12V. When I unplugged the wire then ECU detected correctly that circuit is open or shorted to B+. As the signal is coming from the ECU to the sensor and sensor should be with open collector output i.e. it grounds the signal coming from ECU but does not output any voltage itself, then I don't think poor connection or bad wiring can be the cause of the problem.
I measured resistance between terminal 3 of the sensor plug and ground on engine block and it was 6 ohms. Kind of high for ground circuit, but on the other hand - all the wires of the sensor are coming from the ECU so maybe there should be some resistance. The power supply of the sensor on terminal 1 was 5V, as it's supposed to be.
The 00515 code comes back instantly when I clear the codes when engine is idling. However, when I clear the codes at above 1500 rpm, it does not come back before revs drop below about 1500 rpm again. I tried to change the cam position sensor, but that did not solve the problem. Only change was that now the error code returns immediately after clearing at any engine rpm. Changing the ECU did not solve the problem either. The second ECU (used, not new) shows exactly the same fault code.
So, any ideas? What could cause this problem? The chain tensioner was completely worn and was replaced recently, but that also did not change anything. Timing belt is new, timing marks have been checked.