P0366 Camshaft position sensor

[Tullball]

I recently bought a used 2003 316ti, and started noticing a distinct lack of power from the engine. A bit of probing revealed an error, but I'm having a hard time fixing the issue.

Car:
2003 BMW E46 316ti
N42B18A engine

Symptoms:
Lack of power

Diagnostics:
P0366 Camshaft position sensor 'B' error

The first thing I did was to replace the sensor with a new original BMW sensor (part no. 12147518628), but the issue persists even after clearing error codes.
I've also tried to do some manual readings, and found something that might be an issue. According to this video, the sensor is supposed to be getting a 5V reference supply on the signal wire, but I'm reading 12V both on the main supply and on the signal wire. The video is for the M54 engine, but as I understand it they both use the same sensor - but I'm not sure that means they also have the same reference voltage on the signal wire.
I have no idea why the sensor could be receiving the wrong voltage, or how I should go about fixing it.

If anyone have any idea how to fix this issue or how to diagnose it further, that would be greatly appreciated.

[Tullball]

I was able to trace the signal wire back to the ECU and confirm that the 12V reference is supplied directly from the ECU. I don't know if that means the ECU is busted, as I haven't been able to find any wiring diagrams for it.

[Mayorchuck]

Pull off the cam sensor and check the ohms. Should be about 12.5 ohm between pins 1 and 2 and about 0.4 between pins 2 and 3. It will be zero or way out if it's bad. Would not be the first time a sensor was bad right out of the box.

[bmwdirtracer]

Hmmmmm.....

I can't pull up wiring diagrams for your car. In fact, at home, the newest I can pull up easily is a 2001 Z3, with an M54. Technology should be the same.
http://wedophones.com/Manuals/BMW/20...g%20Manual.pdf

See page 95 of the Adobe document. You'll note that the 12 volt power to the cam sensor comes from a fuse, not the DME. The DME provides the ground, and RECEIVES the signal. What color is the wire you're finding 12 volts on? Or, if you can't see wire color, what pin number of the sensor plug?

How exactly did you "trace the signal wire back to the ECU", if you don't have wiring diagrams?

[Tullball]

Pull off the cam sensor and check the ohms. Should be about 12.5 ohm between pins 1 and 2 and about 0.4 between pins 2 and 3. It will be zero or way out if it's bad. Would not be the first time a sensor was bad right out of the box.

I was unable to measure any connectivity between any of the pins on either the new or the old sensors. Additionally, I pulled off the camshaft intake position sensor, and was unable to measure any connectivity on that one either. At this point I'm not sure whether I'm just really unlucky with broken sensors, or if the car's electrical system is destroying them somehow.

- - - Updated - - -

See page 95 of the Adobe document. You'll note that the 12 volt power to the cam sensor comes from a fuse, not the DME. The DME provides the ground, and RECEIVES the signal. What color is the wire you're finding 12 volts on? Or, if you can't see wire color, what pin number of the sensor plug?

How exactly did you "trace the signal wire back to the ECU", if you don't have wiring diagrams?

Thank you for the link. You are correct that the 12V Vcc is not connected directly to the ECU, the issue is that I'm also measuring 12V on the signal wire, where I think it's supposed to measure 5V. The wire I'm talking about is either black or really dirty (I'm also colourblind), pin number 2.

The way I traced it back to the ECU was to follow the wires to find the right ECU connector, then I tested each pin on the plug until I found the one connected to the signal wire. Then I measured the corresponding pin directly on the ECU with the ignition turned on, which measured 12V.

Edit:
I also measured the signal wire going to the camshaft intake position sensor, which also measured 12V.

[bmwdirtracer]

Sorry for being obtuse, but how did you know which pins on the DME (ecu) corresponded to those particular wires, without a wiring diagram, or cutting open the entire harness?

Also, testing for voltage on the signal wire on a non turning engine is not the way to test a Hall sensor. It's going to have the same voltage as the supply, until the magnet sees an open window of the sensor wheel; then it will show zero volts.

The resistance of a cam sensor is between 500 ohms and 1500 ohms. Resistance testing must only be done on an unplugged sensor. If you read zero ohms between any and all of the pin combinations, your ohm setting of the multimeter is probably bad (which happens if you ohm-test a powered circuit)

[Mayorchuck]

[Tullball]

Sorry for being obtuse, but how did you know which pins on the DME (ecu) corresponded to those particular wires, without a wiring diagram, or cutting open the entire harness?

Step-by-step on what I did:

1: Locate cam-sensor plug.
2: Locate signal wire on plug (pin 2).
3: Follow wiring harness back to the ECU to find the connector containing the right wire.
4: Use a multimeter to measure resistance between signal wire on the cam-sensor plug, and each wire on the ECU-side plug.
5: Keep going until you find the wire on the ECU-side with 0 ohm resistance - you have a wire connected directly to the signal wire on the cam sensor.
6: Measure the corresponding output pin on the ECU.

Also, testing for voltage on the signal wire on a non turning engine is not the way to test a Hall sensor. It's going to have the same voltage as the supply, until the magnet sees an open window of the sensor wheel; then it will show zero volts.

I first measured the wire independently as seen here. The voltage didn't correspond with what was expected from the video, but I don't know if 12V on the signal wire means it's broken, it's really difficult to get reliable sources on what values to expect for each particular engine. I've also just been measuring sensor voltage while rotating the engine, as seen here, for both the intake and exhaust cam sensors. The results were close to what was described in the video, but not exactly the same. The voltage peaks at 12V instead of 5V as expected, but it didn't drop to 0V twice per revolution as mentioned in the video, instead they both dropped to 0V intermittently in a 2-revolution cycle. The voltage drops seemed to roughly correspond with the impulse wheels, as seen here (14). As I understand it, that's the point of the sensor, but I'm a scrub when it comes to cars.

The resistance of a cam sensor is between 500 ohms and 1500 ohms. Resistance testing must only be done on an unplugged sensor. If you read zero ohms between any and all of the pin combinations, your ohm setting of the multimeter is probably bad (which happens if you ohm-test a powered circuit)

I did measure the resistance with the sensors unplugged, but as I don't have a auto-range multimeter, I limited it to 200 ohms the first time around. I went out again and tried to measure more thoroughly, but the measurements I'm getting are so inconsistent that I'm starting to think my multimeter is busted. Unfortunately I have no alternate meters to test with or any resistors to confirm that it's functioning.


I did do another test aswell. Seeing as the intake and exhaust cam sensors are the same type, I reset the error codes and swapped them around. The result was that I got the exact same error code, which leads me to think one of two things are true:

1: Both sensors are busted.
or
2: Both sensors are working.

If only one sensor was busted, I would expect a different error code when I swapped them. If both sensors are busted (and the old sensor which I replaced), I would lean towards something in the electrical system destroying them, anything else would seem like too much of a coincidence. If that is the case, the best lead I have is that the signal wires are outputting 12V, but I have no reliable source that tells me this is wrong, only similar sensors on similar cars.

If both sensors are working, I have no idea what the issue is. Maybe the camshaft timing? I've read somewhere that it's not uncommon for the registry chain to slip on these engines, because the original tightening bolt design was bad.

Anyone have any ideas on what my next step should be?

[bmwdirtracer]

What are you reading the codes with? P-codes are notoriously inaccurate for diagnosing BMWs.

The video is wrong: you won't see 0 volts twice per revolution, you'll see it once every two revolutions of the crankshaft. (The crank turns twice for every revolution of the camshafts).

I cannot explain why the video shows 5 volts, on an E46. Certainly, there have been many cars with 5 volts to the hall sensors, but as you can see from the wiring diagram which Mayorchuck provided, as well as the one I linked to, 12 volts is common on many BMWs of this generation.

My best guess is that your code is incorrect. I'd suggest having the codes read by a BMW specific diagnostic computer which reads in words, not numbers which have to be translated from paper charts.

[Tullball]

I'm taking the car to a shop tomorrow to read the BMW codes and possibly check the camshaft timing, I have neither the equipment or the know-how to do that myself.

[Warrengee]

I'm taking the car to a shop tomorrow to read the BMW codes and possibly check the camshaft timing, I have neither the equipment or the know-how to do that myself.

Hi, did you find out what was wrong as I am having the exact same problem?