Engine check light on again!

[kiwitrains]

3.0 SIDi. Had this problem couple of months ago. P0174 System Too Lean Bank 2 and P0171 System Too Lean Bank 1. Mech changed oxy Sensors both sides ($220 each!). Ran ok for a few weeks light came on again took it back said it was something to do with spark plugs changed plugs checked everything for leaks etc. reset codes again, now comes on again with the two codes as above two mechs cannot find what is causing this and are stuck, engine runs perfectly fuel consumption has not changed reset codes and comes back after a couple of days anybody get any ideas, should I tale it to Holden

 

[vq~gangsta]

The two screws on top of the fuse box under the bonnet have something to do with the earth connection for the ECU. Apparently if they come loose or stripped it can cause funny readings and fault messages. Have you touched these screws at all?

I had a little fiddle withe mine recently then my car wouldn't start and I started getting error messages.

 

[kiwitrains]

The two screws on top of the fuse box under the bonnet have something to do with the earth connection for the ECU. Apparently if they come loose or stripped it can cause funny readings and fault messages. Have you touched these screws at all?

I had a little fiddle withe mine recently then my car wouldn't start and I started getting error messages.

Just checked them and they are fairly loose and cannot be tightened I will get this checked out thanks

 

[vq~gangsta]

Sweet.
Please let me know what you can find out about them as my fault may be intermittent and one of my screws seems to have a stripped thread and cannot be tightened so I'd love to know the fix if you fan find out.

Cheers

 

[Capsule]

I doubt a loose connection would trigger exactly the same error message every time. An earth issue would cause all kinds of random gremlins.

I'd plug an OBD2 scanner and check the fuel trims while looking for any vacuum or exhaust (pre sensor) leak. Could also be an intermittent fuel pump or regulator issue.

Here are some insights:
Fuel Trim?

While scanning run the engine at different RPMs and see how the STFT change. A vacuum leak would cause high STFT at idle, but they would almost go back to normal at 1500rpm and more.
They are tons of tutorials/videos on how to diagnose a lean condition. Very interesting topic and lots to learn.

Enjoy!

 

[kiwitrains]

We think we have solved it, the EVAP solenoid was stuck open slightly so a new one was put in codes cleared and all seems well.

 

[duca1991]

We think we have solved it, the EVAP solenoid was stuck open slightly so a new one was put in codes cleared and all seems well.

Hey mate, has the issue gone away completely ?
I am getting the same issue, hoping its the same thing that needs replacing,
Cheers