Engine Management Light, XM 'W' reg 2.1 diesel auto. 85K

[Geraint11]

The engine management light now sometimes comes on when driving. If I stop and switch off the engine and restart, the light goes out till next time. There appeares to be no difference to the running of the car, but I am concerned that damage may result from running with the light on. I am in WD6 area (Hertfordshire) and would pay for any diagnostic assistance.

Local garage - just leave it with us attitude

Graint

[noz]

Hi geraint,

This may not be exactly what you want to hear but I have been having the same trouble with my daily runabout 2.5TD since I got it. Like you the engine management light would illuminate intermittently seemingly at random. I connected the laptop but in my case I think I have the wrong ecu fitted and so my situation is a little more complicated. The laptop reports that my ecu has a "Permanent Fault". I can howver connect to the ecu and I can see all the sensor values. I tried everything I could to track down the source of the intermittent alarm without success. Looking at all the live values from the sensors, they all seemed in order. Compared to my other 2.5TDs this one has always been a poor performer.

However, on a recent trip to Nairn a couple of weeks ago I was overtaking someone accelerating hard and the enging coughed lightly and made a sort of gurgling noise. The noise was muted and I had the radio on so I couldn't determine from where the noise emanated. For the remainder of the journey a lot of the power that the 2.5TD should have, returned. What's more the engine light has not returned. I plugged it into the laptop again to see if I could determine the cause but the only fault to be found was the intake air temperature sensor. It was saying it had either a short or an open circuit. I cleared the fault and it has not returned. I also looked at the connector on the sensor and took it off and on a few times.

None of that will of course help you find your particular issue but I thought a little anecdotal evidence might not go amiss and to let you know that you are not alone.

Best of luck.

noz

[Geraint11]

Hi Noz

Thanks for your reply - in your opinion, is it worth buying a Lexia to try and find this fault, as this light problem has only appeared in the last month.

As I only drive the car in the summer - use a Ford Scorpio diesel auto for the Winter - also low miles 96K, I would like to sove the problem before I store it away in Oct.

Geraint

[noz]

Hi Geraint,

Hmmm..... that's a tough question because it's highly subjective. I watched the Lexia prices falling for a couple of years before I took the plunge and it was the intermittent engine management light that finally pushed me to buy it. In the event, the Lexia didn't help that particular problem but it has been a useful tool for other problems and other cars. Yesterday I put it on George.C's 2.0 Turbo XM which was suffering from hard suspension and non-working cruise control. We discovered that the switch on the brake pedal was continuously showing closed and therefore the likely source of both problems. I also solved a problem with my sister's C2.

Re-reading your post it dawned on me that you never said what model you have and I forgot to ask. The cause of the intermittent engine management light can be very varied depending on the model/engine type. Can you tell me the model and RP number? For future reference its handy if you put the model and RP in your signature so that when you ask a question the answer is more likely to be more specific to your model. Just click on "My Controls" at the top right hand corner of the screen then "Edit my signature" on the following screen about half way down on the left. Put your car details in the white box.

Cheers

noz

[robertmnorton]

Hi Noz,have been following this topic ,but forgive my intervention.The brake pedal switch is not monitored by the suspension ecu,it is the hydraulic pressure switch in the brake lines that OPENS it's contacts above 3bar applied pressure which causes revertion to firm mode.This was deleted from the DK5 with the introduction of H5 designated ecu's and thence from all subsequent engine variants from 1999 where the H5 was factory fit.I suspect most rhd cars of these latter dates left the factory with H4 ecu's to "h" or "j" revision.The firm reversion status being determined by acceleration/deceleration from speed sensor signals.
The engine management light is indeed difficult to diagnose a cause.In my case with spurious BTE engine run problems i reverted to the oscilloscope to confirm correct signals to/from the ecu.However,the cause was simply an over adjusted accelerator cable giving values outside those in the map for the given conditions,one ring back on the cable adjuster and all was well.This of course is not valid for "drive by wire" of the DK5.The instrument injector fault was confirmed with the oscilloscope having first been identified by the LEXIA.A replacement injector sorted that.
robertm

[Geraint11]

The car is a Xm VSX Turbo Diesel 2.1 Auto Estate. reg date. 30.09.1999

I will change my signature to include

Thanks

Geraint

[robertmnorton]

Hi Geraint,as yours is a BTE engine then have a look at the accelerator cable adjustment as per my previous post.Also,has any tuning mods been carried out,the timing belt changed or the pump adjusted?
The EPIC ecu will throw up an engine management light at anytime the operating parameters are outside the mapping.Usually as a result of incorrect static timing.
robertm

[Geraint11]

I will look at the accelerator cable adjustment on Wed. No mods to the engine, but when the car went for it's MOT in April, the garage managed to jump the timing belt. RAC lifted the car up and brought it home. I removed the head - no damage but replaced the exhaust valves, guides etc and rebuilt with new belts, gaskets & roller tensioner - parts came to £343 including discount.

That was in April - engine light problem started in July.

Can the timing be checked with the engine running - as I used to do in the days of distributers

Geraint

[noz]

Hi Robert,
Hi Robert

No problem at all. It is better to be correct than say nothing out of politeness. My mistake was presuming that the contacts were normally open rather than normally closed whether they had been on the pedal switch or pressure switch. A mis-diagnosis on my part. I should have checked the manual before jumping to conclusions. Another one salted away for future reference.

I suspect you are correct re: the intermittent lamp. A short circuit or open circuit would show up as a permenently recorded or intermittently recorded fault in the ecu memory. When the fault is simply out with the ecu's range i.e. if it is expecting a value between 500 and 1000 ohms, say, and it gets 300 or 1200 ohms, particularly intermittently, it doesn't seem to record that as a fault like it does the others. Thats what makes them so hard to find.

Well done.

Best of luck, Geraint.

Cheers

noz

[robertmnorton]

Hi Geraint,for the correct timing info refer to the 2001 PRIVATE CARS BOOKS for
which Noz has installed a link,but basically once the belt alignment is pinned a further pin is installed in the pump timing orifice and the mounting adjusted to locate the pin before locking up.Much the same as any diesel pump.
The difference is that once set any variance is electronically compensated.The LEXIA will give all parameters,but no adjustment can be made dynamically.
robertm

This post has been edited by robertmnorton on August 16, 2010 10:22 pm

[Geraint11]

Hi all

Just an update - car still the same - 'K' light comes on now & then. Took the car to a Citroen garage who checked the car with both his hand held Lexia and the main unit in the workshop. He said he was unable to connect to the ECU and perhaps there was a fault in the wiring between the diagnostic plug connection in the car and the ECU.

I have had all 8 spheres changed at Pleiades and the cost was lower that buying the spheres myself - 2hrs and all done. Car now floates along.

Looking at the inside of the ECU plug, some of the plug terminals seem slightly out of line as though it has been unpluged a few times in its life - thought perhaps I could send the ECU unit to a specialist for them to check it - any thoughts on that

Still floating along

Geraint

[xmexclusive]

Hi Geraint11

To me the combination of inability to read the ECU and the intermittant fault light suggests high resistance contact connections rather than a wiring fault.
I would be inclined to target the ECU connector first as it is the easiest to get to.
These days I use "Contralube770" on the XM connectors. I find it can be applied to each individual contact and seems to eliminate intermittant contact faults.
Maplin or Rapid stock it. The later diesel XM's seem prone to intermittant engine management light faults. On the later 2.5's I think it is down to the extra emmission controls and sensors playing up. Not sure what Citroen did to the later 2.1's to meet the tighter standards.

John

[robertmnorton]

Hi Geraint,an ecu test will certainly illiminate this component from the diagnostics and give peace of mind.However,i'd be inclined to follow John's advice first.The PSA diagnostic socket can be a problem when connecting the Lexia interface lead.I think most of us have had occaisions whereby several attempts at connection have been made before communication was successful.
robertm

[noz]

Hi Robert,

I'm glad you said that. I have had what can best be described as intermittent success geting my Lexia to talk to the engine ECU. I have no trouble with any of the other ECUs, just the engine one. I thought at first it was a damaged pin on the 30-pin connector or at the ECU plug. I removed the plug from the ECU and did a continuity test between the 30-pin diagnostic socket and the ECU plug. All three pins tested fine.

I just have to accept that the Lexia connects sometimes and not others.

Cheers

noz

[xmexclusive]

When picking up some ebay bits from an Indy a while ago we got talking about Lexias . When he showed me his Lexia (genuine one) I asked why he had two sets of leads. He said that it was because he had found swapping them usually overcame the regular read failures.

John