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2023 Metris P017285 The mixture (cylinder bank 1) is too rich
Currently working on a 23 metris m274 with the P017285, with 40K for mileage. Has anyone else experienced this code with the M274? It runs great at anything above idle. But slowly leans rich at idle to a point where it stumbles a lil. I have replaced the following parts....
Up and downstream oxygen sensors
Downstream map sensor
Fuel rail and injectors, performed quanity adjustment.
Cleaned intake runners and valves
Replaced plugs
Checked low pressure and high pressure fuel pressures. They appear to be normal
Smoothness of operation on the Fuel injectors look good, nothing on the fault counter.
Do not see or hear any exhaust leaks/ air leaks. But I dont have a smoke machine so I can't be 100 percent sure.
Checked amperage and circuit for wiring issues on the O2 sensors per WIS diagnostic procedure. Both look good. I dont see any other data related to Fuel regulation or lambda control that seems wrong other than the upstream O2 senor slowly goes down at idle, the downstream stays consistent around.0.95.
I am fairly new to the Xentry , so maybe im missing something The Xentry is a great tool but does lack on data of some Pids.
Thanks in advance for fellow expertise.
Check the purge valve. If it's stuck open, it will flood the engine with fuel vapor at idle, causing a rich condition. It's a common and often overlooked culprit.
Since you've checked almost everything else, a small vacuum leak you can't hear could also be tricking the engine into adding too much fuel. A smoke test is really the only sure way to rule that out.
Thank you, I did actually check that purge valve with a vacuum tester. And it held a vacuum. I just forgot to mention it. I was also thinking about checking my alcohol content in the Fuel when I go back to work.. I do need a smoke machine . It would be handy.
Currently working on a 23 metris m274 with the P017285, with 40K for mileage. Has anyone else experienced this code with the M274? It runs great at anything above idle. But slowly leans rich at idle to a point where it stumbles a lil.
I have replaced the following parts :
Up and downstream oxygen sensors
Downstream map sensor
Fuel rail and injectors, performed quanity adjustment.
Cleaned intake runners and valves
Replaced plugs
Checked low pressure and high pressure fuel pressures. They appear to be normal
Smoothness of operation on the Fuel injectors look good, nothing on the fault counter.
Do not see or hear any exhaust leaks/ air leaks. But I dont have a smoke machine so I can't be 100 percent sure.
Checked amperage and circuit for wiring issues on the O2 sensors per WIS diagnostic procedure. Both look good. I dont see any other data related to Fuel regulation or lambda control that seems wrong other than the upstream O2 senor slowly goes down at idle, the downstream stays consistent around.0.95.
I am fairly new to the Xentry , so maybe im missing something The Xentry is a great tool but does lack on data of some Pids.
Thanks in advance for fellow expertise.
You have done a real serious job already at fixing this rich idle fault with all the right checks & (genuine) parts for M274 2.0T - 40k.Mi.
Now we can say, you're dealing with something less than obvious that should not be happening at such low mileage.
Something is lightly upsetting idle A/F and it's not a seasoned injector.
ECU should report a negative LTFT (how far off -15% ?)
You report engine issue becomes obvious at idle but runs well above.
I know you did check pressures already... can you read how your high side fuel pressure varies from 700, 1000, 1500, 2000...Rpm and then perhaps the low side feed pump too
Rich engine may have something to do with weak sparks... noted you don't have misfire DTC.
-- Lack of idle air... unlikely. ECU can open throttle plate but must keep Rpm near idle.
-- Rich fault setting is based on Lambda that's already new.
-- How did check injectors for no leak ?
-- Is the engine using signicant vaporized oil (hydrocarbon rich) ?
The smoke machine would let you find leaky exhaust valves passing raw gas to the exhaust during compression (thermal IR camera!)
Last edited by CaliBenzDriver; Nov 1, 2025 at 12:42 AM.
I would try a smoker machine to look for odd leaks. I would also try to swap no1 injector with another to see if you can get the issue to move it is it all no1 cylinder?
There are reports that show that a simple reset on the ethanol sensor gone wild + mixture reset
is the PERFECT FIX.
Think of this as a man-made defect... the ethanol logic screws up the mixture. Perhaps you can find a sort of calibration procedure...
Smoke tested today with nothing found.Leak down tested and ran compression test. Everything looked great. Tested the alcohol content and was less than 10 percent. Scoped cylinders and definitely showed signs of rich mixture. Im going to take the intake off and clean the throttle valve tomorrow.
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