Cam-position sensor error

[Alastair2334]

Hi, I hope this isn't covered here somewhere but I've not been able to find a conclusive answer to this:

I got a check engine light, the OBDII code was P0340 for 'cam position sensor error'. The person at the independant Saab specialist garage told me the problem was the DIC. I bought a new one from the internet and installed it myself since it is so easy to do, and would save a lot of money.

But the error code didn't clear even after driving the car for a while. I took the car back to the same specialist who said that the code was still P0340. He cleared it and said to come back in if it came on again. If it did then the DIC was faulty and needed replaced. He also questioned whether the DIC I had was really new.

Now, I was a bit confused by this because from what I could see there is no way that the DIC can actually be sensing the cam position. And the new DIC I had bought really did look brand new, boxed and in perfect condition.

So I took the car to a different independant specialist and he tells me that the cause is the crank-position sensor. I asked him whether it could be the DIC, and he said they are very resilient and only tend to break once in a cars lifetime. He said that the DIC could not cause this fault, and that any DIC problems would most likely be acompanied by mis-fires. He also mentioned, without me prompting him, that the DIC I had looked as though it was brand new.

He replaced the crank-position sensor today (yet another large bill) and I am now really wondering which one of them is correct? Surely a crank position sensor should cause a P0335 error, according to the list of OBD codes? Though clearly since they are chained together it is just doing a similar thing to a cam sensor.

Can anyone tell me definitively whether a 1999 93 2.0l has a cam-position sensor? Is it located in the DIC? And what would cause the P0340 code?

Many thanks,
Alastair.

[JBob]

Hi Alastair, welcome to Saab Central!

This forum is for the later 2003 on 9-3 Sports models. Your query would be better answered in the NG900 & 9-3 forum located here:

http://www.saabcentral.com/forums/forumdisplay.php?f=15

Good luck!

[john bernard]

Not definitively, but I don't think your car has a cam position sensor. If I remember correctly, Saab WIS says the Trionic system receives information from the spark plugs ( I don't know how)

[Alastair2334]

So I wonder whether that means that the DIC can be involved somehow?

As a further update, the new crank position sensor hasn't fixed the problem. The check engine light came back on again this morning.

[john bernard]

From WIS:

The Saab Trionic system is of capacitive type. It consists of 4 ignition coils and electronic circuitry built into the ignition discharge module. The ignition coils are controlled by the electronic circuitry in the ignition discharge module, which is in turn regulated by low level outputs from the ECM
When the engine is cranked, the ignition system produces a spark on two spark plugs simultaneously, 1 and 4 or 2 and 3, for a number of consecutive complete combustion processes. Following this, on the basis of the ionization current flowing through the spark plugs and signals from the crankshaft position sensor, the system has sufficiently reliable information for synchronizing spark generation and fuel injection to the correct cylinder.

[john bernard]

Add'l comment: It appears there are three components: DIC, CPS, and spark plugs.

[Alastair2334]

I forgot to mention that the car also got new spark plugs about two months ago. So with new plugs, a new crank-position sensor and a new DIC that's a bit worrying, and makes me wonder whether it really could be a problem with the replacement DIC I got?

[john bernard]

I would check to make sure that the plugs are the ones recommended by Saab and that the gaps are correct.Apparently 'ionization current' through the plugs is very important.

[lancelot8602]

I hope you kept your original DIC because it might not be bad. I know it's rare but seldom does a bad DIC give you warning (CEL light), they usually just die and the engine will not start. A classic symptom of a bad CPS is stalling when warm and maybe a CEL.

I wonder if you have a short somewhere, I say this because any of these items (DIC, CPS, plugs) should cause noticable symptoms. If any of these are going bad I would expect bad idling or misfires, stalling, no start, bad gas mileage. Anything else happen other then a CEL?

[Alastair2334]

The spark plugs themselves should be the correct type (they were fitted by an independent saab garage a couple of months ago) as the person at that garage diagnosed the old ones as a possible cause for the check engine light.

There are no signs of any other problems at the moment. Perhaps the idle is very slightly rougher that I'd have thought it should be, but I might be wrong about that. There are none of the signs of a usual ignition problem, like rough running, stalling, coughing or problems at start-up. The car will run right up the rev range too, so it doesn't appear to be in 'limp-home' mode.

Thanks for all the replies, with so much help I feel more confident I'll get to the bottom of this.

Thanks,
Alastair.

[Alastair2334]

There is a new development in the cars behavior: When I had it in neutral at the traffic lights it very occasionally gives one small stutter followed by the revs being kicked up (presumably by the engine management system) and then it settles again.

That seems to me a lot more like an ignition problem .

I took the car back down to the garage this morning but they were too busy to work on it. Should be back in there again tomorrow though.

There hasn't been any stalling while warm (or at any other time) though this new development does feel a bit like it could stall just before the revs get kicked up. And that is with a new crank-position sensor installed so I assume that's not causing it.

I do still have the old DIC. I was planning on just keeping it in the boot as a 'get me home' part in case the other DIC ever failed. As you say though it may not be bad. Either they're both bad, or neither, or one of them. At the moment my money would be on neither being bad.

Given that the DIC & spark plugs are the only parts on the 'high voltage' side of the ignition, is there any chance that it could be a problem with the wiring on the low voltage side (presumably a problem with the wiring leading to the DIC might cause the same problems as the DIC itself?)?

Is there any chance that the actual computer management system might be causing this? I've not seen any posts here about problems with the electronics in these cars.

[Cesare]

Have you ever checked that the spark plugs were the right ones? The cost should be a giveaway. My mechanic has charged $9/each for the wrong ones and $29/each for the right ones.
Oh, and since the crank sensor code was on he changed the plugs AND the crank sensor, a $99 part plus $162 in labor.
Now my question is: what are the chances that the crank sensor code was caused by the wrong spark plugs?

[Alastair2334]

Hi guys,
I know this thread has been moved to the correct section, but since people are still posting here I thought I would give you the final outcome:

The problem was solved by installing another new DIC. I went through every other possibility. First the spark plugs, then the crank sensor, and eventually the DIC. I was fooled by the fact that I had replaced the DIC with a brand new one that I bought off ebay. It really was genuinely brand new, but I don't know where they got it from. Probably out of a dumpster behind the saab factory when they realised they were defective...

Anyway, that ebay DIC really confused me for a while and cost me a lot of money while I went through replacing all the other parts.

From what I understand, the 'cam position sensor' error reading is mis-leading. There is no actual cam position sensor in these cars as there was in others (I think the 900 has one) but the engine management system still needs this signal. They get round this by some electronics in the DIC that takes the crank shaft sensor signal and presumably halves it's frequency (since you get two cycles of the cylinders for every camshaft rotation). So it was the electronics in the DIC that went wrong.

The second problem, where the car would rev slightly when in neutral has gone away. Maybe it took a while for the car to re-learn some settings after the new DIC was fitted? I don't know.

Thanks for all the replys. I'm very happy to finally have no engine-warning light.

[jstrowe]

If the problematic new DIC does not have a Saab dataplate on it, it's not from Saab. I bought one of the Chinese knock-offs and it was a waste of money. It looked good, but it only ran properly for about two months, then things started going wrong.

John