Engine malfunction, increased emissions

Hi folks,
I attended a track day last weekend, nothing wrong during the day and then I left the car parked in garage for 4 days. Last Thursday I drove the car and engine malfunction came up after driving it for about 1mins. I parked the car and restarted it, engine malfunction disappeared and the "check engine light" and "increased emission" light went on. This light remained on until the car is completely warmed, and I parked it for about half an hour. Then i restart the car when it's warm, all lights disappeared and the car feels just normal. This process repeat for every cold start.
I took the car to a local BMW dealer, they said this was caused by boiled brake fluid leaking into brake boost sensor and damaged it. They also claimed my brake was over heated and unsafe to drive. Interestingly I just swap my pads with hawks street racing pads front and rear and flush my fluids with torque product right before the track day. Came back from the dealer, I double checked my brake fluid reservoir and found no liquids ever leaked out and brake fluids level is at max.

Has anyone experienced similar issues and is "brake boost sensor" really the cause?

My car is 2011 DCT competition pack e92 m3.

Anyone had similar issue?

The fluid dripping onto the sensor is a known problem, you just have to be very careful when changing or topping off the fluid. There could also be a very small leak.

The generic warning message you got is probably not related to that. It is just that: very generic. Any auto parts store can pull the warning code for you to see exactly what the issue is. It's a free service.

I just had my local auto parts store read my codes to be P1209.(Brake Booster Pump Shutoff Valve Plausibility)

Hi folks,
I attended a track day last weekend, nothing wrong during the day and then I left the car parked in garage for 4 days. Last Thursday I drove the car and engine malfunction came up after driving it for about 1mins. I parked the car and restarted it, engine malfunction disappeared and the "check engine light" and "increased emission" light went on. This light remained on until the car is completely warmed, and I parked it for about half an hour. Then i restart the car when it's warm, all lights disappeared and the car feels just normal. This process repeat for every cold start.
I took the car to a local BMW dealer, they said this was caused by boiled brake fluid leaking into brake booster vacuum sensor and damaged it. They also claimed my brake was over heated and unsafe to drive.
Interestingly I just swap my pads with hawks street racing pads front and rear and flush my fluids with torque rt700 right before the track day. Came back from the dealer, I double checked my brake fluid reservoir and found no liquids ever leaked out and brake fluids level is at max.
Had my local auto parts store read codes to be P1029.

I flushed my brake system when the car was off(no brake assist when pressing the brake petal to flush brake fluids), could this cause possible damage to brake booster or sensors related to it?

My car is 2011 DCT competition pack e92 m3.

I intermittently got an increased emissions warning that would clear if I shut the vehicle off. About a month later the car went into limp mode. I ended up with two new throttle actuators.

Like the above poster said though, it could just mean the car is setting a pending code for the ECM and is generic.

Couple of links for future reference in this thread:


List of ECU error codes in this thread.

Here is the P1209 direct link.



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