Scan Codes P0171 & P0174 Help Please

[ReflexSonic]

Hi ive just done a scan on my 95 SC430 to see why i have the ECL displaying. The scan reports two codes which are:

P0171- System to lean bank 1

P0174 - System to lean bank 2

the ECL only came on after an Independent services the car. Thinking it may be air intake related (as its both banks) ive checked to see if the air filter was replaced (and properly) it was and all appears to be well.

Is it possible that the engine and system needs time to adjust to the new clean air filter?

Also the last owner used Premium Fuel where i use regular unleaded EN10, could the change of fuel have an affect?

I look forward to any feedback and advice please - thank you

[Spock66]

41 minutes ago, ReflexSonic said:

Is it possible that the engine and system needs time to adjust to the new clean air filter?

Could be it's not been fitted properly or there is a loose hose, also check the oil filler cap is done up tight.

I would be inclined to rule out a vacuum leak as the first possible cause.

[ColinBarber]

1 hour ago, ReflexSonic said:

Is it possible that the engine and system needs time to adjust to the new clean air filter?

Also the last owner used Premium Fuel where i use regular unleaded EN10, could the change of fuel have an affect?

 

No and No.

Given that both banks are affected it is likely to be an air leak in the intake somewhere after the MAF sensor (e.g. a vacuum pipe) or the MAF sensor itself (did they try and clean the MAF)? The other possibility would be leak in the exhaust but where the two banks join in the middle of the floor is probably too far away from the O2 sensors for them both to be triggered.

[ReflexSonic]

36 minutes ago, ColinBarber said:

No and No.

Given that both banks are affected it is likely to be an air leak in the intake somewhere after the MAF sensor (e.g. a vacuum pipe) or the MAF sensor itself (did they try and clean the MAF)? The other possibility would be leak in the exhaust but where the two banks join in the middle of the floor is probably too far away from the O2 sensors for them both to be triggered.

Hi many thanks for your reply @ColinBarber i checked to see if the air filter has actually been replaced and it has. Ive since run the car and it now seems to be almost perfectly smooth on tick over? maybe it wasnt quite seated right? could i be that lucky? ive only give it one run and no ECL yet but i expect that will come on at second start up tomorrow?

I will keep updating till cured and then find something else to fiddle with and ask daft questions

Many thanks for your help guys im loving all this meddling it reminds me of my teens

[ColinBarber]

1 hour ago, ReflexSonic said:

maybe it wasnt quite seated right? could i be that lucky?

That shouldn't matter because the MAF sensor is after the air filter so it will correctly measure the amount of air entering the engine even with leak around the filter. But if they loosened the clamp that holds the air filter housing to the intake (circled in green below) then that could allow air in after the MAF (circled in red). Check that the hose is pushed in correctly and the clamp is tight.