E46 330Ci Engine Warning Light

E46 330Ci Engine Warning Light

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Argybargy

Original Poster:

247 posts

181 months

Saturday 25th October 2014
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This came on. Engine felt a bit hesitant at low revs. Otherwise ok (except for the flipping pinking which won't go away).
Garage did diagnostics and replaced a coil pack and lambda sensor. All ok for 48 hours...but now it's back.

Garage thinks it might be the cats but at a quoted £1200 (which sounds a rip off) I'm not keen to try unless I'm convinced that's the problem...which I'm not.

Never heard of this problem on the forum so would be happy to hear from someone who has experienced this.

E30M3SE

8,465 posts

195 months

Saturday 25th October 2014
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Do you know what brand of coil & O2 sensor have been used on your car?

Argybargy

Original Poster:

247 posts

181 months

Saturday 25th October 2014
quotequote all
I believe they are BMW parts, although the garage was rather disparaging about the quality - the coil packs in particular.

E30M3SE

8,465 posts

195 months

Saturday 25th October 2014
quotequote all
If they fitted genuine BMW part then there should be no issues with quality.

Have they read the codes on the car again?

Argybargy

Original Poster:

247 posts

181 months

Saturday 25th October 2014
quotequote all
I'm on my second replacement set of coils and they've always been genuine BM parts. The garage was able to recover the cost of the coil under warranty.

The car hasn't been back to the garage (a BMW specialist) since the problem re-occurred but I'm not optimistic they will able to pin point the problem.

I've never heard of cat problems on the E46 so that is a real concern.

stevesuk

1,345 posts

181 months

Saturday 25th October 2014
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Off the wall suggestion - Have a quick check of the two section rubber hose/ducting between the MAF/airbox and throttle body.

Common for them to split or crack, causing unmetered air to enter the engine.

Mine had a large split on the underside - and gave a similar feeling of slight vagueness/hesitation at low revs (sometimes made it hard to pull away from junctions smoothly). It also occasionally triggered the engine management light for short periods of time.



If you do find a leak, you'll notice with the engine running that when you cover it up, the idle RPM changes immediately.

Argybargy

Original Poster:

247 posts

181 months

Sunday 26th October 2014
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Steve - thankyou. Checked but all seems ok. MAF sensor was replaced not so long ago. Standard air filter has been replaced with a Pipercross panel filter but they shouldn't have anything to do with it.

Matt_N

8,900 posts

201 months

Sunday 26th October 2014
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How does the DISA valve sound?

Poor low rev performance, a pinking sound and EML could be DISA related?

It's the back box on the side of the inlet manifold.

verbarthe

73 posts

195 months

Sunday 26th October 2014
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You could try taking your oil filler cap off and giving it a good clean making sure it s on fully tight. Had the EML come on my 330ci Convertible and just could nt find the reason why at all, turned out it was the seal on the oil filler cap , I had nt turned it on closed fully . Anything that lets in excess air to the engine will cause the EML light to come on .

Edited by verbarthe on Sunday 26th October 21:15

Sardonicus

18,928 posts

220 months

Sunday 26th October 2014
quotequote all
Yep check the intake boot shown as an un-metered air leak will create an excessively weak mixture thus causing engine knock along with the engine light on because the oxygen sensor wont be able to command the ECU to supply enough fuel (and the ECU will see this lack of response/feedback) frown quite easy to read out if the live data is studied by someone who is able to interpret whats going on and why nerd

Edited by Sardonicus on Sunday 26th October 21:38

Argybargy

Original Poster:

247 posts

181 months

Wednesday 29th October 2014
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Thankyou to all for your help.

Back from garage. Fault codes show 'Catalytic converter efficiency' for both banks 1 and 2. Fault codes reset but will no doubt reappear in a day or two.

Cost of two replacement cats c. £1,250 incl fitting. Yikes.

This doesn't seem like a common problem for E46s. Car is not used for short journeys and always run on good quality super unleaded.

I will have to speak to a cat specialist to see if either the cats can be cleaned or there is a lower cost replacement available.

StuntmanMike

11,671 posts

150 months

Wednesday 29th October 2014
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I keep getting this, just on bank one though.
Swapped around the coil packs, as the fault originally said miss fire on number 5.
I then checked the intake system, and replaced the DISA valve.
I was going to replace the lambda.
My car runs perfect, except for one thing, start it from cold and after a minute it will start to run really rough, start from cold and drive away, no problems.
Where I am now is the yellow EML will come on after 3 or 4 days of driving, code p 420.

Argybargy

Original Poster:

247 posts

181 months

Wednesday 29th October 2014
quotequote all
Exactly what mine was doing. Replacement of coil pack and replacement lambda sensor has resolved uneven filing and poor response at low revs.

But the cat problem remains...

Garage advised definitely not Disa valve.

helix402

7,832 posts

181 months

Wednesday 29th October 2014
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Does the car have a running problem or just a warning light, are the emissions ok?

Argybargy

Original Poster:

247 posts

181 months

Wednesday 29th October 2014
quotequote all
The car is Now going really well since replacement of the dodgy coil.

Passed its MoT last month no problem so assume emissions ok.

Garage advises that further degradation of the cats will lead to progressive loss of performance - but this isn't evident at the moment.

Edited by Argybargy on Wednesday 29th October 23:23

FurtiveFreddy

8,577 posts

236 months

Wednesday 29th October 2014
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I've been having trouble like this for a few months now. Two lambda sensors and a replacement cat later, the engine light still comes on, usually after a 1 hour drive. Idle is slightly rough at times and when the light comes on the engine feels flat and lacking power.

I've got an OBDII cable and INCA software so I can read the codes and clear the faults but don't know what to look at next. I'm beginning to think the lambda sensors were never faulty and it's something else which hasn't been diagnosed yet.

Luca Brasi

885 posts

173 months

Thursday 30th October 2014
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I had a similar issue on my 325i, runs on 98 fuel only. Engine light came on, had codes checked, dealer said cats needed replacing. They reset the light and it hasn't come back since, engine runs whisper quiet, 105k on it.

helix402

7,832 posts

181 months

Thursday 30th October 2014
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Here are some suggestions:

Fit lambda probe extenders (fit between the cat and sensor) to trick the sensor into thinking the emissions are ok

Have a remap with the sensors programmed out

Fit a pair of used cats

Buy a cheap obd reader and reset the code when it is annoying