P0343 code questions.

I have a 2000 996 Cab with this CEL engine code. The code is for "Cam Position Sensor Bank 1 signal out of range." Of course it's impossible to get to the sensor with the tiptronic gearbox in the way so ... the engine came out. Changed the sensor, checked out the wiring harness from the sensor to the big round engine harness connector. All three wires are good. The engine went back in, I scoped out the signal at the engine bay side of the harness while the engine is running and saw a good signal, about 90% duty cycle, 12V 90% of the time, and 0V 10% of the time. So the signal is good. The error code P0343 came back despite the good signal. What does that mean?

I would suspect it means the cam timing is off.

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That would makes sense but ... the live data read by the scanner shows the Actual Cam Angle to be 0.00 degrees, cam deviation to be 0.00 degrees. It does not read any values. The same data for bank 2 is within sensible range, and fluctuating a bit as the car is running.

This is the Cam Position Sensor signal from Bank 1: It means the sensor is getting 12V The sensor is working (it's new) And the signal wires are not crossed or shorted with anything

A few things to consider:: The tab on the camshaft for the CMP sensor could be damaged or out of position, you can see it barely if you remove the rubber cam plug on the rear of the head. Make sure the cam timing is physically correct. Both CMP sensors bank 1 and 2 are connected on the same data wire, so both signals should be seen at the same time. The DME distinguishes which one is bank 1 and which one is bank 2 .. Since both signals are sent over the same wire, and the DME decides which is which, it can get all confused. I have seen this before and had to do a "hard reset" of the DME to clear up this confusion.

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I will check the cam timing via the two plugs at the rear of the heads (toward the rear of the car). As for the two signals being combined, the wiring diagrams show two Cam signals (pin 2 of the connectors) routing out to two different pins on the large round connectors. Are you saying they are brought together some place else before the ECU? How do you do a hard reset of the DME?

I think Porschetech may be thinking of the cable throttle ME5.2 engine, which does have the cam position sensors tied together. My schematic for the ME7 E-gas engine shows them with independent wires to the DME. I would add some more context to that scope picture, perhaps the other bank's cam position sensor to see the relative timing. I agree the signal looks perfect.

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Opps, sorry, my comment was pertaining to 97-99 models with DME 5.2.2...where the CMP signals from both bank 1 and bank 2 do indeed combine at a point before the DME... I just noticed you have a 2000ym and DME 7.2 which has separate CMP signals all the way to the DME...

Context: This car was a basket case before I got it. I did not run well, had huge plumes of smoke white/blue, lost coolant, over 10 CEL codes, noisy pulley, and excessive cam deviation on bank 1. The engine came out, a bunch of things were changed/fixed, new MAF New roller over valves new tensioner pads on bank 1 (cam shafts removed, retimed with Sirtools timing kit) Tensioner pads on bank 2 inspected (cam shafts removed, retimed with sirtools timing kit) new AOS, new pressure relief valve at coolant tank Two new O2 sensors (pre cat) A few other odds and ends Engine went back in, car runs pretty well, has good power, but after three on-off cycle the CEL came on with the code P0343. Engine came back out, Cam Sensor bank 1 removed and a new one went in. Wires from sensor to big round connector measured out to be good. Two wires were added to the cam signal so I can hook up an oscilloscope when running. Engine cam back in, fired up, runs well enough, but engine code P0343 came right back. Put a scope on the two signal wires (Cam signal and Ref ground) and the above is the signal I got. Could I have messed up the cam timing on one bank and not the other? Possible, but it does not explain why the live data shows 0.00 degrees for Actual Cam Angle, and zero degree for Bank 1 deviation. Done for today but when i can, I am going to rip out the back of the car to get to the ECU and scope out the Cam signal to see if it makes it to the computer. And I will remove two cam plugs to see if the cam timing is close enough. Why would it read zero degree cam angle?

If you completely disconnect the sensor do you get a different reading? Perhaps the circuits in the DME are faulty.

Make sure you do a full �reset� of the ECU. A few years ago I was getting a cam position sensor code ( I think it was 0321 but I�m not positive - there�s a long thread on it here somewhere). In any case, after doing a complete engine out, cam chains, pads etc. the code came back... It wasn�t until I actually removed the ECU to check for physical faults (there were none) and then reinstalled it the the code went away and didn�t return... Magic?

As part of the engine out, the battery was disconnected for 3 days. After the engine went in, before it started, I read the code and saw no DTC. After a short run the code came back. Clearing the codes with the scanner while it's running, it would return immediately. So, are you saying removing the ECU is a hard (harder) reset than battery disconnect? If not, what is a hard reset?

I might try scoping both cam position sensors at the DME/ECU to rule out a wiring issue between the round plugs and the DME, and to make sure there is not a wiring mixup. The cam position sensor signals should be 180 degrees out of phase. I fixed a longstanding drivability issue on a VW that had the cam position sensors plugged into the wrong banks; the wiring harness colors were swapped by the factory which fooled the technician. I'd also scope the signal with the cam position sensor in question unplugged.

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Modern Automotive electronics have LOTS of small capacitors in them. They act like small batteries and charge up with power and store the power for hours/days/even weeks. It is enough to sometimes keep Memories alive, and Memories can have stored corrupt data. The only way to be 100% certain that all memories are cleared is to completely disconnect the battery, and either touch the positive and negative cables together, or connect a test light across them to completely drain all stored power/clear memories. This is referred to as a "hard reset"..

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Thank you. That is clear.

Update: Oh what a tangle web we weave ... when we fooking do not have the right information. At a loss for what else can be wrong, I checked the Cam Sensor Bank 2 Signal at the CPU. Triple checked the pin and the wire colors. There is no signal there, zero, nada, flat line to GRD. So despite the Launch Scanner, the Actron OBD2 scanner, and the Durametric Pro all saying this Code P0343 is Bank 1, it's actually Bank 2 that is bad. This weekend will be for finding out why it is bad.

So I spliced in a wire from Cam sensor 2 signal to pin 19 of the 3rd connector at the ECU. These are the cam signals at the CPU. I don't know if the relationship of the signals is right. Cam 1 on top, cam 2 bottom. It's time to get into the cam timing.

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What I'm saying is that there was some sort of "memory" in the/my ECU. I can't explain the why, where or how - I can only give you anecdotal evidence of what happened in my case. My engine was probably out for close to a month as I was only able to work on it for a few hours a night, and I wound up doing a bunch of other stuff while I had it out (clutch, water pump, IMSS, cam chains/pads, tensioners, AOS etc...). Upon getting everything back together, the CEL/code came back (even though my cam deviations were back within spec.) Each time I would clear the code with Durametric, it would come back after a short time. I decided to remove the ECU and check the main board for signs of trouble there (there were a couple threads where folks had described similar behaviors and found burnt caps, and/or de-soldered chips on the ECU). I removed the ECU (following all the grounding/anti-static instructions/warnings) and checked it for damage. I found nothing obvious, so I buttoned everything up and re-installed it making sure all the multipin connectors were well seated and locked. Upon starting the car the CEL went out and never came back... Take it for what it's worth... Good Luck

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I can't say if that relationship is correct either, I can say for sure the signals are not shorted together and both appear to be electrically correct. When I was troubleshooting a similar issue on a different car I found it valuable to have the crank position sensor signal on the scope. There's a zero mark in the crank position sensor - two missing teeth on the wheel. By referencing the cam position sensor to that crank zero I was able to figure out that the flying magnet on the camshaft had come adrift. While this exact problem can't happen on an M96 as it uses different technology the concept is the same.

Let me give a final update: In the end, I found that the cam timing on bank 1 is 1/2 of a chain link off. It was obvious once the cam cover came off and I counted the links between the two cam sprockets. Six and 1/2 links, not 7. Reset it, put it all back, and fired it up. It is running smooth and no more P0343 code. I'm done.

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When you say "reset it", do you mean you adjusted the sprocket/cam timing? The reason I ask is because this should have been done originally. Was it missed? ie: never timed/adjusted, or did the sprocket slip (ie: the bolts weren't tightened/torqued properly? Sorry for the "40 questions" - just might help someone in the future...

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I changed the worn out tensioner pads and was not careful during the process so one of the two sprockets moved just a bit on installation of the tensioner. Reset it means "removal of cam shafts to the bench, compressing the tensioner with the factory tool, turning one sprocket to the correct position (7 links away from the other one), reinstalling the tensioner, putting the whole thing back in the car, installing the hold down tools, making sure the slot on exhaust cam is perfectly vertical and fits into the Baum cam tool, install cam caps and tensioner bolts to specs, install cam cover with black silicone, and exhaust components etc.".. ; and fire it up then checking Deviation values with a scanner. All is well.