Q: Q: Check engine light

asked by on

O2 sensors (running Lean) and now blue smoke has been coming out of tailpipe not all of the time.

My car has 75000 miles.

The engine running lean could be due to using the wrong air filter and or the mass air sensor is defective. Check to see you are using the correct air filter and replace it if you are not using a factory filter, before the mass air sensor is replaced. The smoke you see may be the engine using extra oil from the restricted intake air filter. This causes the engine to suck in excess oil into the cylinders and puts it out the tail pipe. It’s also possible that you have overfilled the engine oil. I recommend having the systems checked by a mechanic with the correct scanner for your BMW. They will be able to look at the O2 sensors fuel control before and after the filter is changed. Also, the technician will check if the mass air sensor is in need of replacement in order to sort out your Check Engine Light.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Q: Check engine light

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Service Engine Soon light going on and off.

Sometimes a code will set under certain criteria and while your driving the criteria goes away and the computer recognizes it and it turns the light off, this is normal operation, but that the light comes on it should save...

Q: De-ironized water or tap.

You should not use tap water since it has added chlorine, calcium, and other additives that de-ionized water will not. You can purchase coolant already pre-mixed 50/50 or mix it yourself with de-ionized water and coolant mixed 50/50. You can...

Q: Where is the fuel pump relay located bmw 328i xdrive 2009

The fuel pump relay is located in or on the engine cowl. It may be on the passenger side beneath the air intake. Orange is a common color used by BMW for the fuel pump relay housing. YourMechanic does offer...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...