Skip the auto shop - Our mechanics make house calls

Q: CEL light P171 p174 codes fuel trim always single digits

asked by on

weather idling or driving .. long and short term trim never into double digits

My car has 75000 miles.
My car has an automatic transmission.

A: If you're lean on both exhaust banks, t...

If you're lean on both exhaust banks, typically there would be a vacuum leak causing the issue. Even a small vacuum leak can cause fluctuations in fuel trims and BMWs are a little more sensitive to point out engine operation problems. The DISA valve is a common spot for vacuum leaks and drivability concerns if the valve does not function properly. Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look at your check engine light troubles and offer a more personal diagnosis.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Heated windshield not working.

It appears that you may actually be experiencing two different issues with your Mustang. I do not believe the two are related so we will look at each concern independently. In regards to the rear window defroster, it is quite...

Q: Possible bad VSS

Depending on the code retrieved from the computer, I would assume your assumption is correct. Replacement of the sensor is not very difficult. The sensor or wiring might be damaged. Replacing the sensor may or may not be necessary....

Q: I changed my fuse for the lighter a fuse fell ou next to it I put it back now car starts but will not drive could u help please

Without seeing the fuse box and which fuses fell out this may be tough to diagnose. Try checking the immobilizer fuses (12/37) to be sure they are in the correct place and not burnt. If this does not work, you...

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...