EGR & Lambda DTCs

[A lex]

Been for another drive.

Fault back within 5km (dip in power during acceleration, followed by yellow triangle, then drives OK again).

This time faults on:

-Ho2S
-MAF

Then, whilst sat in the car I got a temporary TCM to ECM comm failure too.

This leads me to the following ideas:

1. The battery is old and could be knackered - ive ordered a replacement, not a bad idea to do in any case. This could be causing CAN comms failures and errors.

2. The o2 sensor has been common to both events - so if the battery doesnt fix it, ill get a new o2 sensor.

3. If its still buggered I guess its time to start thinking along the lines of ECM !?!

[Coldrow]

Originally Posted by A lex

A month after changing both the DPF temp sensors, the yellow triangle of doom reappeared on the dash today. Luckily no limp mode.

Fault codes are:



Economy has been a bit poo lately, gearchanges a bit sudden, and it sounds a little rough sometimes at idle.

At the end of the month we have a 5k euro tour coming up, so cant afford to be fannying around with it too much - a quick and permanent fix needed.

Im thinking replace the o2 (lambda) sensor as a first fix and take it from there..... sound reasonable?

Same fault as what I'm getting at the moment.. but if you drive any distance in it it will eventually trigger limp mode.

I've cleaned my EGR valve out but it wasn't too gunked up on an 06 model with 130K on the clock. One tip if you are following VIDA for the removal of the EGR is that you don't need to removed the Heat Exchanger bit from the back of it. Leave the clip on that connects it to the flexible steel pipe but remove all other fixings. You can then maneuver the whole assembly to gain access to the 4 screws (M6 Caps) at the back of the EGR assembly.


I've noticed on mine that the signal from the EGR will "stick" so is interrupted but only when the engine bay is hot. Limp mode has been triggered when stationary in traffic after driving for a while so the latent heat in the engine bay increases. This is leading me to believe the wiring is at fault which is my next port of call. I've just traced the pin allocations on the ECM from the block connector on the EGR.

The stepper motor for the EGR and sensor are all contained in the black part on the front of the EGR valve. Easy to remove. I "bench" actuated my EGR to see if it worked as it should, which it did.

Good luck

[diro]

Originally Posted by A lex

Been for another drive.

Fault back within 5km (dip in power during acceleration, followed by yellow triangle, then drives OK again).

This time faults on:

-Ho2S
-MAF

Then, whilst sat in the car I got a temporary TCM to ECM comm failure too.

This leads me to the following ideas:

1. The battery is old and could be knackered - ive ordered a replacement, not a bad idea to do in any case. This could be causing CAN comms failures and errors.

2. The o2 sensor has been common to both events - so if the battery doesnt fix it, ill get a new o2 sensor.

3. If its still buggered I guess its time to start thinking along the lines of ECM !?!

I have been reading the whole your thread. I think you are going wrong dirrection now or intended to go wasting your time, money and losing temper lol

A month ago as you said you replaced DPF sensors. THATS THE PLACE WHERE YOU SHOULD LOOK FOR THE ISSUE. Your DPF filter. Sorry for the capitals but I hope you will pay attention on that
Your DPF is clogged most likely. Its very unlikely both sensors die at the same time if filter is OK. When its clogged extreme temperatures rise and do damage to the sensors, turbo charger etc. You dont see black smoke coming out simply because DPF stops the soot.

Check DPF with Vida and perform a forced regeneration if Vida will allow you to do that. Depends on the DPF differential pressure/soot level.

MAF fault you have can be caused by the boost issues. And the boost issues can be caused if you have boost leak or turbo charger problem. Again that problem can be caused by DPF.
And if DPF is clogged the soot builds up everywehere especially in EGR. Soot cause EGR performance issues.

Good luck!

[A lex]

Hi Diro,

Yes you make some good points.

I certainly dont think all the components are failing at the same time - much more likely that there is one central source causing a multitude of false readings.

Im heading out now to do some live data readings and will also measure the DPF soot content.

Cheers

[A lex]

Had a chance to play this afternoon; some observations:

- It didnt produce the fault whilst I was live monitoring it - typical!

- Alternator function tests as OK (but only just), which suggests the battery has seen better days. Quite happy to be changing that tomorrow.

- DPF had 18.5g of soot, which is just below the 'cruising burn weight' according to VIDA. Nothing to worry about there. I did a forced regen anyway, and took soot down to 10g.

- I re-initialised/calibrated the following:

DPF pressure sensor
MAF
EGR position sensor
(and another one I forget!)

So a new battery tomorrow, and then drive it to see if the fault comes back in the next few days. Having seen that the DPF only had 18g in there, im not overly worried about is functioning now.

[Funky Diver]

Thankfully I don't have a DPF in my car (I think) =D

It's more diesel voodoo that I don't really have a complete handle on yet, lol. I grew up on points and plugs and went on from there =D

[Rooster]

A forced regen should empty the filter straight off,

if it isn't you have an issue,

The regen temp should get to 650'c or around that on the post cat sensor, if its not then its a distint possibility you have a faulty 02 sensor,

altho it still might be worth pulling pipes off either side of EGR valve and giving it a clean, you can do quiet a good job without actually having to remove it as there abit of a pain to get off

[A lex]

Todays progress:

Changed battery.

Did an aerosol EGR clean (not for the faint of heart, but seems to work well!)

Cleaned the electrical connections on the ECM and the HO2S.

Even if it doesnt fix the glitch ive been having, it was worth doing the above as its now driving much, much smoother.

(Before changing the battery I left the IGN II on to see how long it would be before the 'low voltage' warning. No accessories were powered, radio off etc - it took 7 mins! So in any case it was time for the battery to be replaced!)

Ive got to commute in it tonight, so im mildly curious if the triangle of doom will return!

[A lex]

Also verified that the old battery was genuinely kaput.

20mA draw (with the boot light on as well), so a perfect reading and no unwanted current drain

[Coldrow]

Not wanting to hijack your thread but I think you may be onto something with cleaning the connections to the ECM.

I was getting sporadic readings for my EGR valve where the sensor would "freeze" although the ECm required had changed. When this happened it threw it into limp mode.

I checked all my wiring with a multimeter from the EGR plug to the ECM and it all seemed fine so I too brandished the contact cleaner as a "couldn't hurt" measure.

Went for a drive while live monitoring and things seemed to be better with the 2 EGR values mirroring each other nicely without any lag.

I've not read any suggestions about cleaning the ECM plug/connections but thinking about it it is a logical place to start looking first.