S63 lambda fault

[Al14hos]

Hello
Everyone, hope you are all well.
I need some help. And initially I’d like to say I understand this is a different model section to my car (BMW M6), but my understanding is the f10 M5 and F series M6 share very similar, near identical engine configuration etc. so wanted some help please.

I have a bmw M6 2014 s63 cab.

Has downpipes and cold air intake fitted by me. And it’s been mapped once by a tuner but wasn’t happy with the map, but no faults.
I’ve purchased and swapped over to BM3, firstly had the stage 2 tune 93 no faults, then moved to stage 2 aggressive map and after a few miles I now have the engine light on and fault: 12B304
Heating lambda probe bank1, control: line break

Read by BM3 and also engine light on. I can clear it but it install re-appears.

After research I found (but I’m likely wrong) this is the lambda for the drivers side (UK CAR) downpipe. So I get a tested used one and fitted it but still have the fault. Have switched back to the stage 2 non aggressive map and have the fault.


Any advice would be great full, as I said I may not even be changing or looking at the correct sensor but when looking on the web (mostly m3/4 topics come up) with that fault and that’s the solution.

Look forward to your replies and in desperate need as I need an MOT.

[M5Rick]

So with downpipes, I gather these are catless?

[Al14hos]

Hi
Yes thank you for your reply, they are catless downpipes, then latter in the exhaust (where the resonator normally is it has 100 cell sports cats)

It is mapped however so that it’s is catless.

[M5Rick]

I'm not great with tuned engines but I would swap the cold air intakes, behind the grille? for the stock ones and go from there but first clean the MAF's (which you've probably already done) and see if it makes a difference.

[TinCanSailor]

There are two sensors on each side one pre cat and one post cat. Check that they are both plugged in. Antoher issue I have seen is that some cats do not have the bungs in the same height or position as the factory cats. Sometimes installs just dont seat the sensor all the way as a way to help the sensor cable reach the wiring harness plug.

[Al14hos]

Thank you for both your replies.
As for the MAFS, following your feedback I have removed cleaned them and refitted, but to no luck.

As for the cat sensors. With a tune I didn’t think the secondary ones need to be plugged in, as correctly said by yourself I had bungs fitted. I’ll give that a try and see?
Something I should say though, initially fitting the Downpipes and tune I didn’t get any faults


Is there any other testing you guys can recommend?
Something I should add I’ve realised is on idle the car keeps slightly increasing and decreasing its RPM. It’s little but noticeable by ear and if yku keeping a close eye on the Rev counter. Any thoughts on that?

[M5Rick]

If the tachometer is 'hunting' then try cleaning the MAF's with CRC spray cleaner if you haven't done so already.
Tell us a bit more about it like what the mileage is and when the spark plugs were last changed and with a tune like that you may need colder plugs like some others on here have mentioned. Check the fuel filler vent pipe if it's not blocked.

[M5Rick]

Also what petrol do you use.

[Al14hos]

Hello
Thank you for your messages.

Try to only use Shell power.

I’ve cleaned the mafs with Carb cleaner.

It’s full service history but done 60,000 miles

Standard plugs. Not sure but believe they haven’t been done.

What I find strange making me think it’s odd is that as soon as the faults cleared it comes back instantly. Just by turning the car on. No driving or anything for the car to take in like low air levels etc? Maybe I’m wrong. Not sure trying to get advice.


You don’t happen to know a good guide for changing the spark plugs on this engine?

Thanks
Ali

[M5Rick]

Originally Posted by Al14hos

Hello
Thank you for your messages.

Try to only use Shell power.

I’ve cleaned the mafs with Carb cleaner.

It’s full service history but done 60,000 miles

Standard plugs. Not sure but believe they haven’t been done.

What I find strange making me think it’s odd is that as soon as the faults cleared it comes back instantly. Just by turning the car on. No driving or anything for the car to take in like low air levels etc? Maybe I’m wrong. Not sure trying to get advice.


You don’t happen to know a good guide for changing the spark plugs on this engine?

Thanks
Ali

Your problem could be too old plugs and it may be worth going for one step colder ones for your tune, always best to ask a tune expert for advice.
Try the Texaco Ultimate 99 petrol, it has no added ethanol reported in the last test. I started using it with Redex petrol additive, it primes the injectors and lowers co2, good to add before MOT and at every fill up.
Not all texaco stations stock it so look up the Ultimate pdf for your nearest station.
I take mine to BMW to change the spark plugs of which you get that two year parts and labour warranty, though there are DIY guides on google.

...Just to add that BMW may refuse to change plugs if car is tuned and parts warranty will be void.

[M5Rick]

Originally Posted by Al14hos

Hello
Thank you for your messages.

Try to only use Shell power.

I’ve cleaned the mafs with Carb cleaner.

It’s full service history but done 60,000 miles

Standard plugs. Not sure but believe they haven’t been done.

What I find strange making me think it’s odd is that as soon as the faults cleared it comes back instantly. Just by turning the car on. No driving or anything for the car to take in like low air levels etc? Maybe I’m wrong. Not sure trying to get advice.


You don’t happen to know a good guide for changing the spark plugs on this engine?

Thanks
Ali

Should only be a proper MAF cleaner and nothing else.

[Al14hos]

Thank you for your reply.

Right I’ll get a set of spark plugs gapped correctly

And I’ll give the Maf’s another clean. But when searching MAF cleaner I get sprays coming up for “intake and carb” mostly and when I search CRC I get contact cleaners. Happy to buy either if they’re what you mean is better? Or if you have used a specific one before?

I’ll try the redex too.

Didn’t know about the Fuel, will search and find my nearest station.

To give me a bit of confidence I’m going to search the forum for guide on changing the plugs. If anyone has a good link please do let me know.

Thank you

[M5Rick]

Here's a vid on plug change if you want to go that DIY route.
For the CRC MAF cleaner it's easiest to order from e-bay
https://www.google.co.uk/search?q=m5...id:qEsSdxGKztA