Check engine light HELL! ... Please Help

Hi all,

Hope you can share your experience on this.

I have been in check engine light hell for the last 3 weeks and in for >$1,700.

Here is the sequence. First, the car...E90 M3 with ~64K miles on it. Literally zero issues in the last 5.5 years I have had it.

Check engine light came on a few weeks ago. Took it in to an independent shop and they read a current fault 2B59 Coolant Thermostat Monitoring and a sporadic fault of 27AF Secondary Air pump. The check engine light had come on for cold start 2x before last summer. Turned the car off-then on and it was gone.

They replaced the thermostat and I was on my way ... EXCEPT ... first cold start the light came on. Took it back and they read a current 27AF. I was highly skeptical that two emissions oriented things would go wrong at exactly the same time (again, on a car that has had 0 issues).

I took it into another shop. They found the output hose to the pump was disconnected. The replaced but didn't fix it so they replaced the secondary air pump.

2nd cold start and the light was back on. Took it back and they assured me it was the air mass meter that is on the output host. Replaced that and 2nd cold start it is back on.

Anyone else have anything similar happen? Thoughts on this being the ECU (which would still be under warranty)?

Any comments are greatly appreciated.

Thanks,

Justin

I would get the codes read again, preferably by a reputable shop! Seems the shop is experimenting on your dime by replacing parts without proper diagnosis..

jbhnc wrote

Hi all,

Hope you can share your experience on this.

I have been in check engine light hell for the last 3 weeks and in for >$1,700.

Here is the sequence. First, the car...E90 M3 with ~64K miles on it. Literally zero issues in the last 5.5 years I have had it.

Check engine light came on a few weeks ago. Took it in to an independent shop and they read a current fault 2B59 Coolant Thermostat Monitoring and a sporadic fault of 27AF Secondary Air pump. The check engine light had come on for cold start 2x before last summer. Turned the car off-then on and it was gone.

They replaced the thermostat and I was on my way ... EXCEPT ... first cold start the light came on. Took it back and they read a current 27AF. I was highly skeptical that two emissions oriented things would go wrong at exactly the same time (again, on a car that has had 0 issues).

I took it into another shop. They found the output hose to the pump was disconnected. The replaced but didn't fix it so they replaced the secondary air pump.

2nd cold start and the light was back on. Took it back and they assured me it was the air mass meter that is on the output host. Replaced that and 2nd cold start it is back on.

Anyone else have anything similar happen? Thoughts on this being the ECU (which would still be under warranty)?

Any comments are greatly appreciated.

Thanks,

Justin

27AF - P1411, Post-51

2B59 - P0128, Post-2

You could have just spent $1000 on a tune which could have also disabled the secondary air pump and cold start

kerrit wrote  

You could have just spent $1000 on a tune which could have also disabled the secondary air pump and cold start

True

jbhnc wrote

Hi all,

Hope you can share your experience on this.

I have been in check engine light hell for the last 3 weeks and in for >$1,700.

Here is the sequence. First, the car...E90 M3 with ~64K miles on it. Literally zero issues in the last 5.5 years I have had it.

Check engine light came on a few weeks ago. Took it in to an independent shop and they read a current fault 2B59 Coolant Thermostat Monitoring and a sporadic fault of 27AF Secondary Air pump. The check engine light had come on for cold start 2x before last summer. Turned the car off-then on and it was gone.

They replaced the thermostat and I was on my way ... EXCEPT ... first cold start the light came on. Took it back and they read a current 27AF. I was highly skeptical that two emissions oriented things would go wrong at exactly the same time (again, on a car that has had 0 issues).

I took it into another shop. They found the output hose to the pump was disconnected. The replaced but didn't fix it so they replaced the secondary air pump.

2nd cold start and the light was back on. Took it back and they assured me it was the air mass meter that is on the output host. Replaced that and 2nd cold start it is back on.

Anyone else have anything similar happen? Thoughts on this being the ECU (which would still be under warranty)?

Any comments are greatly appreciated.

Thanks,

Justin

Let me know if I can help with scan tools. I am in the Charlotte area

Likely not the ECU. It could be the Mini HFM there, or it could be a potential blockage in the system.

I wouldn't spend any more money on it, would get a tune which will solve that.

Mike Benvo wrote

Likely not the ECU. It could be the Mini HFM there, or it could be a potential blockage in the system.

I wouldn't spend any more money on it, would get a tune which will solve that.

Wish everything can be that easy...

Bad or weak battery will give you fits, Personal knowledge.
$$$$ but 2008 models are past battery life with few rare exceptions.

chuck
2009 m3 with a new battery and driven daily 50miles a day

what is the secondary air mini-HFM? I'm getting the 2739 code as well as 27C5 and have no idea what the mini HFM is referring too? Any help appreciated.

Thanks

chuckvic wrote

Bad or weak battery will give you fits, Personal knowledge.
$$$$ but 2008 models are past battery life with few rare exceptions.

chuck
2009 m3 with a new battery and driven daily 50miles a day

Had same type of stuff on my 08 when the battery was on the way out.

Mike Benvo wrote  

Likely not the ECU. It could be the Mini HFM there, or it could be a potential blockage in the system.

I wouldn't spend any more money on it, would get a tune which will solve that.

What if he wants to fix the car to OEM specs? Not everyone wants a tune!

BMRLVR wrote  

Mike Benvo wrote  

Likely not the ECU. It could be the Mini HFM there, or it could be a potential blockage in the system.

I wouldn't spend any more money on it, would get a tune which will solve that.

What if he wants to fix the car to OEM specs? Not everyone wants a tune!

If he wants to chase down/fix the problem, no one is stopping him. Might cost more time and money than a tune would.

Mike Benvo wrote  

BMRLVR wrote  

Mike Benvo wrote  

Likely not the ECU. It could be the Mini HFM there, or it could be a potential blockage in the system.

I wouldn't spend any more money on it, would get a tune which will solve that.

What if he wants to fix the car to OEM specs? Not everyone wants a tune!

If he wants to chase down/fix the problem, no one is stopping him. Might cost more time and money than a tune would.

You are correct it may cost him more, but, that doesn't change the fact that he may not want a tune. Let's see what the OP wants to do!

BMRLVR wrote

What if he wants to fix the car to OEM specs? Not everyone wants a tune!

BMRLVR wrote

You are correct it may cost him more, but, that doesn't change the fact that he may not want a tune. Let's see what the OP wants to do!

Wow, you've really been beneficial on this thread. Maybe instead of bitching at someone's response that would solve the problem, you should put your effort into helping him solve the problem.

I would say next time it throws a code, take it to a different shop, and if they dont seem confident, another one. I wouldnt continue to let a shop experiment on with a "blank check." That being said, I would just delete the cold start with a tune because that way you arent chasing around a problem.

OP, has your battery been replaced ever for your car? I don't know much about coding but, to me, it seems to be a relatively cheap, quick fix to try. Some of the info in this post seems to make it a plausible fix.

One poster mentioned he had similar troubles as you that was fixed with a new battery. Your comments about the CEL coming on seem to have gotten worse over time which would make sense for a dying battery. First sporadically, with the CEL disappearing after the next turn on. Then permanently after the 1st and 2nd starts.

Seems like a code would be thrown for something as simple as a dying battery or possibly an alternator not providing enough power. But again, I don't know much about coding.

With the multiple things being "determined" to be the problem by the shop (thermostat, secondary air pump, air mass meter, etc.), maybe the common problem with these parts throwing errors is just a lack of amperage/voltage allowing them to work correctly.

If you find that your display clock is losing minutes of time over the course of a week, that was an indicator I saw when my battery was in need of replacement. If you've managed to go 5.5 years on the original battery, you should be looking to replace it anyway.

Whatever the solution becomes, please reply with what it was. I am going on 5 years of ownership at 44K miles, so I'm interested to see how it turns out.

Good luck!

Unless there is a specific issue with the battery then changing it is just another way of throwing money at the car with no idea of the outcome. Get a CTEK mxs battery tender for $50 instead if you think low battery charge might be a component of the problem.

Follow the trouble shooting info in the links by regular guy.

You either have a bad air pump, bad air pump relay, or wiring issues either to the air pump or the air flow meter on the air pump.

Highly unlikely it is the ECU!

SenorFunkyPants wrote

Unless there is a specific issue with the battery then changing it is just another way of throwing money at the car with no idea of the outcome. Get a CTEK mxs battery tender for $50 instead if you think low battery charge might be a component of the problem.

Yeah luckily you can have your battery tested at a number of places.

BMRLVR wrote  

Follow the trouble shooting info in the links by regular guy.

You either have a bad air pump, bad air pump relay, or wiring issues either to the air pump or the air flow meter on the air pump.

Highly unlikely it is the ECU!

I don't think anyone said it was the ECU itself. But let's keep talking about it!

BMRLVR wrote

Follow the trouble shooting info in the links by regular guy.

You either have a bad air pump, bad air pump relay, or wiring issues either to the air pump or the air flow meter on the air pump.

Highly unlikely it is the ECU!

Hate to bump a old post, but this is only one of the few remotely helpful post coming up for this issue.

I followed the instructions and benched tested relay, bypassed relay socket, and checked wiring connector to the pump. They all work (pump puts out good air when bypassing relay). The battery is also brand new and voltage reading is fine.

The “air flow meter on the air pump”, is that the one on the suction hose going from intake to secondary air pump? Or is there sensors in the downstream/pressure side too?

Thanks