S40 (New) Engine 2.0D : ECM / CEM problem

[PhilDix]

I have a 2006 S40 2.0D SE and I'm looking to see if anyone has had a problem like mine

I was getting an intermittent hesitancy and limp mode without any messages, so I hooked up the VIDA

I got a number of codes including
ECM faulty glow plug. (No problem starting)
ECM 242F DPF fault. (New one fitted 6 months ago)
ECM 2452 DPF Pressure sensor fault
ECM 2453 DPF pressure sensor faulty signal
I also have ECM C301 Control module faulty software checksum but this has always been there

Checked the pressure and they were high but within spec to do a regen (70Hpa)


Ran the DPF regeneration which seemed to run ok

Ran the pressure checks again and they were within specs and the alarm cleared

I ran the car for the day until the problem started again
Same codes appeared but the pressure checks showed over 120Hpa

Thought I'd run the regen again which again seemed to be ok. But when I shut down and restated the engine to check the pressures the car suddenly ran the revs into the red and did look like it was going to stop,si I switched off

After that it won't start again with the codes reading
ECM 1563 Engine switch off faulty signal

Did all the checks relating to this and nothing amiss

Other odd codes appeared

ECM 2262. Turbo contral valve

And one about the brake lights switch

At this point I decided to remove the battery and give it a charge which would give the ECU a chance to reset itself.

This morning with a freshly charged battery 12v showing on VIDA, still no start but the some codes have all disappeared but I'm left with a new one
CEM 3A00 Software fault signal
ECM C301 Control module faulty software checksum
ECM faulty glow plug

This now looking catastrophic is there a procedure after replacing a battery?

Is there a way of resetting the CEM ans ECM , I've looked under vehicle Comms > advanced. But there doesn't appear to be anything relevant

Any advice and or help would be appreciated

[Bungo]

Has water got into the CEM ?

[PhilDix]

Thanks for the reply

I don't thinks so as the car hasn't moved since this started and all was behaving normalish before the regen

[Bungo]

Terminals can get corroded, maybe worth a look see, other than that it's a process of elimination.

[paddyred]

As bongo says I would (with the battery disconnected for 10 minutes) disconnect the CEM and check for corrosion on the pins. Its unlikely to cause the redline issue as that would have to be a high voltage to give it max RPM and corrosion causes a low voltage unless as said there is water in there. If there is water/corrosion then IPA and a paint brush on the terminals will remove it. Considering all the faults are CEM based and not "physical" but software related I would suggest there is an electrical short not a mechanical issue.

[PhilDix]

Thanks for the feedback
It certainly looks voltage related ad I charged the battery again last night and tried again and initially all faults cleared. Tried starting and got the usual suspects but not the CEM fault but when the volts dropped to around 11.8v up she came.
So I'm looking do what you guys have suggested only I can't find the CEM module. All VIDA says it right at the front with an arrow. Any clues?

Thanks

Phil

[paddyred]

The CEM is fitted in the passenger foot well under a scraggy looking piece of carpet under the glove box. Look underneath and you will see the piece of carpet with two plastic rivets holding it on. Push the centers of the plastic rivets in (try not to loose the center bits) and pull the rivets out, the carpet will then come out the way. You will then see the white plastic CEM and it is held in with two Dzeus fasteners that need to be turned about 90 degrees and the CEM will then drop down exposing all the fuses. If your going to unplug it then you can lift up the back a little and pull towards you and it will come completely free exposing the plugs at the rear.

You say that you have a voltage of 11.8v? Where and how are you measuring that? A healthy battery should be about 12.6v and the system voltage when the car is running should be 13.8v-14.2v. If you have a multi meter then put it across the battery terminals and verify the voltages your getting as you shouldn't be getting 11.8v from anywhere really. The cause of your problem might be a faulty alternator voltage regulator as opposed to a CEM issue if you get no faults untill the voltage drops to 11.8v.

The computers seem to be super sensitive to voltage. I had my battery go flat after I had an early start and dimwittedly left my sidelights on! I had headlight failure warnings, alarm system failure warnings and all sorts of issues until the car charged itself back up again and realized it wasn't broken!

[Achmed TDT]

I feel your frustration! I changed from standard BP to BP Ultimate...MAN, what a transformation! Thought i'd sussed it as they're sensitive to fuel,due to DPF clogging,being a common fault and they're the same engine as Ford TDCi/Citroen/Peugeot HDi and constantly going into 'limp mode' on acceleration,or load uphill. As a result of the DPF issue,they're also sensitive to the oil, even good stuff won't do, it has to be low ash content (Volvo recommend Castrol 5/30 Synth) Also,even a little overfill, causes issues! The diagnostic was Snap-On expensive kit,so not Wang-Chung Chines special on e.bay and after doing everything,was still showing codes like 'DPF pressure sensor not communicating, but still showed it at 60% full? How can it not communicate,but show the level?? Then it was showing turbo pressure etc,etc. Again, after DPF clean, and reset,it went like a stabbed rat, then once again back to limp, although,since the fuel change, limp mode is quicker and smoother? Looked through history and about 2wks before i got it, it had a battery changed! Alarm bells rang! I phoned the garage who fitted it, played ignorant and asked if there's a procedure? They said, yes,but they don't bother!! Without following the procedure it CAN blow the ECU! I've done everything but....... So the next step is an ECU check/repair. I'll keep the forum updated on my progress...if i don't give up and sell as 'Spares/Repair!