Engine Management Light Misery

[jinjacolin]

Hello everyone, I have a fabia 06 plate 1.2 htp and over the last few months the orange/yellow engine symbol comes on intermittently (on for a few days then off for a few days). The fault code states "bank 1 too rich". A local garage has looked at it several times and they can't find a problem so just clear the fault. I took it to a skoda dealer who diagnosed it was a servo pipe which was replaced. The light came on a week later so back to skoda who said it was a cam sensor and replaced, week later light back on! Took to another garage who said it was likely to be the oxygen sensors, had new ones fitted. Yes you guessed it - a week later the light is back on and this time the light stayed on permanently.

Back to the garage and they said an engine air intake sensor needed replacing, eml light came back on after a week. In each case it has been exactly a week from repair to eml coming back on.

If a sensor was to blame why does it take a week before light comes back on? I have spent a lot of money on this and just want to solve the problem so the EML doesn't come back on. The garages and Skoda do not know what the problem is can anyone please help to resolve this?

Can anyone help shed some light on what else it could be so I am not bled dry of money? Many thanks

[jinjacolin]

Someone must be able to help please please please.

[sepulchrave]

I would replace the ECU coolant temperature sensor, cheap and easy and often to blame.

[steve95]

Could be something like an exhaust leak or a split pipe somewhere

[jinjacolin]

Hello sepulchrave, thats on list when I go back to garage tomorrow, many thanks for the heads up.

Steve, I had a exhaust leakage test done and all ok.

I will get fault codes from garage and post here for more detail, thanks guys.

[Robbbbie!!]

It sounds like you have a bunch of "Technicians" who are just guessing. I take it one of the fault codes will be P0172.

 

Post up the other codes when you get chance.

[jinjacolin]

Hello fellow skoda owners.

 

Ok just got car back from garage after having a new engine air intake sensor and a new ecu coolant temperature sensor fitted. The fault code read as follows "16804 CAT. SYSTEM BANK 1 OPERATION BELOW THRESHOLD P0420 INTERMITTENT"

 

Thank you to all those that have contributed.

[sepulchrave]

Intermittent cat fault would suggest dodgy wiring or connection to the post cat lambda probe since you've already replaced the probe itself.

[rossa123]

one the light has been reset/cancelled all the parameters within the ecu are set to zero and then the checking/monitering sequence starts - it can take up to a week for the light to come back on dependant on mileage, turns of the key etc - 

you can buy a diagnostic for approx £35 ( I use Autel - delivered from USA) that will read and delete so at least you are getting the codes yourself -

[jinjacolin]

Hi,

 

Thank you for the great responses. The ECU air intake (MAP?) sensor and the ECU coolant temperature sensor were replaced and the EML has come on again, so back to the garage. I will pass on the info about "dodgy wiring/connection for the post lambda probe" and see what they say this time.

[jinjacolin]

Hi again everyone, well after having the MAP sensor and ECU coolant temperature sensor replaced, the light stayed on permanantly, I took it back to the garage who had a other look. They reported that a minor leak was found near the flexipipe and they have repaired it. I spoke to them about the CAT may be the problem and they dismissed it. The car has been serviced and MOT and passed all ok, they did reset the fault after checking for leak again but alas the light has come on 2 days after it was in the garage. 

 

Not being a mechanic I am now seriously hacked off and don't know what is the best course of action now. The fault codes are the same "16804 CAT. SYSTEM BANK 1 OPERATION BELOW THRESHOLD P0420 INTERMITTENT" I have no idea what this fault code actually means, if anyone knows could you please tell me in idiot terms, and if anyone has had the same codes and solved it could you please share your experience. Currently I am looking at the cost of replacing the while exhaust system (CAT and all) so that I can eliminate parts that could be responsible.

 

If there is anything I can do DIY please send in recommendations, I have followed other DIY guides on here with good success.

 

Many Thanks to all those who have contributed, I would be grateful for any future advice in solving this problem. My garage have told me to just ignore the light as they have been over the car several times and cant find any fault. However the light is on for a reason and I just want to stop throwing money at random solutions and solve the problem.

[Breezy_Pete]

That fault code means that the ECU is not happy that the cat is working efficiently enough. It can be ignored if the car is running OK otherwise, it's just an EU legal necessity for the car to monitor its own cat from a certain date, as you've seen it may well still be perfectly capable passing an MOT, which is all that really matters. The ECU looks at the relationship between the signals from pre- and post-cat oxygen sensors, and can infer that the cat is or isn't working well.

 

What is the engine code of your 1.2? What sort of journeys does it mostly do? Lots of short urban trips?

 

I don't think that anything in the exhaust system after the second oxygen sensor can have any effect. Even the flexi-joint is a fair bit after the post-cat oxygen sensor so unlikely to affect anything (other than audible noise).  We certainly got no warning lights when our flexi was well and truly leaking.

 

I think if I couldn't ignore the light, I'd fit a low-mileage secondhand  genuine cat if it were my car (because I have such an item 'just in case', acquired cheaply at my leisure). Only a few hours DIY work as long as the pre-cat oxygen sensor comes out OK, and it should in your case as it's recent.

 

I guess there are probably other (engine) faults that could cause it to appear to be the cat at fault even though it isn't, so it would be a gamble to replace the cat, but as said, a reasonably priced gamble if you can acquire and fit the thing yourself.

[jinjacolin]

Hello Wino,

 

My engine code is a 6Y2, my journeys are mostly 30 miles to work and some 8 miles to go shopping/friends. I am contemplating changing the CAT to see if that cures the problem, but I have not been able to find a DIY how to guide. I am looking to see if it is something I can do myself or would I have to get a garage to do? I don't want to ignore the light in case another fault develops and I do not pick it up because the light is already on.

 

If I replace the CAT would I need to get it calibrated or VAG Comm'ed?

 

 

Many Thanks for replying to my post. 

[Toxicvrs]

Hello Wino,

My engine code is a 6Y2, my journeys are mostly 30 miles to work and some 8 miles to go shopping/friends. I am contemplating changing the CAT to see if that cures the problem, but I have not been able to find a DIY how to guide. I am looking to see if it is something I can do myself or would I have to get a garage to do? I don't want to ignore the light in case another fault develops and I do not pick it up because the light is already on.

If I replace the CAT would I need to get it calibrated or VAG Comm'ed?

Many Thanks for replying to my post.

That's model code iirc the 1.2 is either AWY BMD or the other one that I can't remember - says under boot carpet on sticker!

[Toxicvrs]

Guessing it's AWY but not definite! Think it's same as mine!

[Breezy_Pete]

That's not the engine code, you're looking for a 3-letter sequence. For 2006 1.2s that will be either BMD or BME, I think.

 

I don't know of a how-to guide for cat change, but it is basically remove pre-cat oxygen sensor, remove heatshield (rad fan may have to come off to make room). Then undo three nuts that hold exhaust front pipe to cat, remove 8 nuts to unbolt manifold/cat from head, replace gaskets, fit replacement manifold/cat with new nuts, re-fit oxygen sensor, heatshield and any other bits you've removed to make space.

 

Nothing to calibrate.

[Toxicvrs]

Right -

1) remove engine cover

2) remove top oxygen sensor

3) undo two top hex bolts and 2 bolts on body of heatshield and remove!

4) get under car and remove 3 downpipe bolts

5) remove manifold bolts

6) withdraw cat and old gaskets

7) replace cat and gaskets in position

8) do up manifold bolts

9) do downpipe bolts

10) refit heat shield using new bolts if old ones are rusty! Use copper grease to aid future removal!

11) Refit oxygen sensor putting copper grease on thread!

12) replace engine cover

13) take for a drive as light may not go out instantly or get code reset with hopefully no reoccurrence

[sepulchrave]

It's possible that the cat has had it but to be sure cook it up good and proper first with a nice long motorway run, take it down the M4 somewhere for a nice day out.

[jinjacolin]

Hi All,

 

Engine code is BMD. Thank you for the guide on how to remove the CAT. How do I know if the CAT is knackered?

 

From speaking to the garage, although they have made some patch repairs to the exhaust, they say the exhaust is in good condition with no leaks and have basically said to ignore EML light. I have to go to Wales so will give the CAT a good run through on the M4, should I use some CATACLEAN  before getting a new CAT?

 

Many Thanks

[Toxicvrs]

Hi All,

Engine code is BMD. Thank you for the guide on how to remove the CAT. How do I know if the CAT is knackered?

From speaking to the garage, although they have made some patch repairs to the exhaust, they say the exhaust is in good condition with no leaks and have basically said to ignore EML light. I have to go to Wales so will give the CAT a good run through on the M4, should I use some CATACLEAN before getting a new CAT?

Many Thanks

I'd take it to a garage that can measure emissions output and compare it to the norm. Iirc cataclean isn't a permanent fix!

[jinjacolin]

Hi all,

 

Been back to garage today, they want to put in a new 'air flow meter' and see if that solves the problem and if that doesn't work I said I want a new CAT installed.

[Toxicvrs]

Hi all,

Been back to garage today, they want to put in a new 'air flow meter' and see if that solves the problem and if that doesn't work I said I want a new CAT installed.

Ask how much they will charge for cat supply and compare to carparts4less.co.uk

[Breezy_Pete]

Hi all,

 

Been back to garage today, they want to put in a new 'air flow meter' and see if that solves the problem and if that doesn't work I said I want a new CAT installed.

 

This worries me twice.

 

Firstly, I don't believe your car has any such device as an 'air flow meter'. It has a MAP sensor that calculates how much air is going into the engine but you say they've already changed that. 

 

If you get them to fit a new cat there are a few pitfalls.

1) most aftermarket cats are very low quality, so may not last very long at all. New genuine would be truly frighteningly expensive I'd say, don't go there.

2) it'll cost a great deal for them to supply and fit it, (upwards of £300 I'd guess for some really cheap and nasty aftermarket thing.)

3) it may not fix the problem, which would be infuriating.

 

Compare this with buying a secondhand genuine item for say £40 or £50; fitting it yourself or with help (where in Berkshire are you?) and the satisfaction you might get from fixing it yourself, for very little cash.

 

** Do the long/fastish motorway run suggested and see if there is a change first. i.e. fault lamp goes out, or comes on less often afterwards. **

 

If you are worried about having the light on and other faults being obscured, spend ~£27 on a scantool so you can check for codes yourself, regularly. The one I bought from Gendan seems to work well, and is very small so can be left in the car at all times.

[jinjacolin]

Hello,

 

Thank you for the great advice, in respect of the 'air flow meter' I will go back to the garage and clarify this. I had thought of buying a second-hand CAT and having a go at fitting myself (I would get a kick from this), however how would I know if that CAT was any good to use and the honeycomb hasn't been damaged internally?

 

I am in Farnborough Hampshire.

 

Silly question - where can I get a second hand reputable CAT?

 

Just to clarify the EML stays on permanently now, as far as I am aware any leaks from intake or exhaust have been repaired and O2 sensors, MAP sensor, ECU temp sensor are all new. Therefore I am led to believe its either the O2 control or the CAT. 

 

I am going to Wales tomorrow so I will give it a nice long blat down the M4 from Bracknell to Cardiff. Just hope I don't breakdown lol.

[jinjacolin]

Ok quick update, I brought some CATACLEAN and used as directed and also did a long run to Wales to see family. On the return journey the EML light went off and I felt some progress had been made but alas the light came back on 4 days later (which is an improvment from being constantly on). I have put a second bottle of CATACLEAN into the tank for another clean and will now look at replacing the CAT.