Jump to content

Fuel trim system too lean


Recommended Posts

The epc light is on all the time. Pal who is a mechanic checked the codes P0171/P1151 which bascially say running far too lean. He checked for any leaks and cleaned the throttle body and valve. He couldnt find any leaks and the problem is still there. I have searched previous threads on here but nobody seems to have got an answer.

Has anybody ever got to the bottom of this problem?

Getting desperate

Trout13

Link to comment
Share on other sites

Check fuel pressure and injectors,not common but either could cause a lean mixture

Leak in the intake system is a more likely cause so the best way to locate a leak is to Smoke test for leaks

Make sure mixture adaptations are reset after fault is found

Have you got the car long? It's possible a previous fault was found and rectified and adaptations were not reset which would cause these faults also

Link to comment
Share on other sites

My pal has cleared the fault a few times but im not sure he reset adaptations. It is not a VAG computer he uses but a generic/andriod one that does various makes. Will he be able to reset adaptations using this do you think? So when you clear the fault code it does not reset to a default setting?

I have the car for about 1 1/2 years, fault started about 9 months ago.

Link to comment
Share on other sites

16555/P0171/000369 - Fuel Trim; Bank 1: System Too Lean

Possible Causes

  • Mass Air Flow Sensor (G70) defective
  • Intake System Leak(s)

Possible Solutions

  • Check Mass Air Flow Sensor (G70)
  • Check Fuel Pressure Regulation
  • Check Fuel Pump
  • Check Injectors
  • Check Intake System for Leaks
  • Check Exhaust System for Leaks
  • Check Secondary Air System for Leaks
  • Check Vacuum Pipes for Leaks

17559/P1151/004433 - Long Term Fuel Trim Additive Air; Bank 1; Range 1: System too Lean

Possible Symptoms

  • Malfunction Indicator Lamp (MIL) active

Possible Causes

  • Intake System faulty/leaking
  • Fuel Pressure, Fuel Pressure Regulator and Fuel Pump faulty
  • Fuel Injectors faulty/leaking
  • Exhaust System faulty/leaking
  • Activated-Charcoal Filter/System faulty/leaking
  • Secondary Air Injection System faulty/leaking
  • Lambda/Oxygen Sensor(s) before Catalytic Converter faulty
  • Lambda/Oxygen Sensor(s) after Catalytic Converter faulty

Possible Solutions

  • Check Intake System for Leaks
  • Check Fuel Pressure, Fuel Pressure Regulator and Fuel Pump
  • Check Fuel Injectors
  • Check Exhaust System for Leaks
  • Check Activated-Charcoal Filter/System
  • Check Secondary Air Injection System
  • Check Lambda/Oxygen Sensor(s) before Catalytic Converter
  • Check Lambda/Oxygen Sensor(s) after Catalytic Converter

Link to comment
Share on other sites

  • 3 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.