Q: Car runs lean, check engine light on

asked by on

Lately, my car started to run lean. I've had several repairs done on it. I changed the spark plugs, the fuel filter along with the fuel injector number one. The manifold has been replaced as well. Also, I changed the MAP sensor purge valve. Despite all the repairs, the check engine light is illuminated again and the problem persists. What do you suggest I should do next?

Hello. Thanks for writing in about your 2009 Audi A5 Quattro. If you are having a lean condition, then the fuel pressure needs to be checked. The most common cause of a lean code on this car is either low fuel pressure from a failing fuel pump or a bad air flow sensor. Both need to be tested to see which one is causing this. If you want to have this done, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the Check Engine Light and come up with the appropriate repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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
  1. Home
  2. Questions
  3. Car runs lean, check engine light on

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: At highway speeds, car loses power

I would check the fuel pressure (for being low) before doing anything else. If it is, check the fuel pressure regulator. (A clogged catalytic convertor would be a constant problem, not intermittent as you describe.) A professional mechanic, like one...

Q: One cylinder doesnt seem to be firing.

If the engine was running fine before the injector swap out, then the cylinder that is not working properly has an injector that is not working. I recommend installing new injectors and not re-manufactured injectors as they can fail. If...

Q: Fuel line or spark plugs at fault. Car won't start, even with a jump.

Get this problem inspected by a mechanic. The most likely failure will be the fuel pump and filter. I would recommend you have a certified technician check for fuel pressure and replace the fuel pump and filter. If the fuel...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...
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...