My check engine light is on and once it's cleared it keeps coming back on "running rich".

Asked by Jan 08, 2014 at 10:36 PM about the 2009 GMC Sierra 1500 SLE 4WD

Question type: Maintenance & Repair

I have a 2009 gmc sierra that is
"running rich". The last few times I
started it, it's been having trouble
starting up and twice it's stalled out
and I had to restart it. Took it to a
local shop and they cleared the light
after they said it was running rich.
Why does it keep coming on?

2 Answers

102,285

A few things, ECT sensor could be out of specs or sending the wrong signal, ACT sensor could also do the same, fuel pressure too high, EGO sensors plugged up or bad, the best way to find the problem is take it to a shop that has a scanner that can do live data while driving down the road, that way they can watch all of the ECM's inputs and outputs and locate the ones with a problem.

1 of 1 people found this helpful.
670

I changed all my sensors on my 89 gmc when i was having ther same problem. Nothing fixed. Took to my mechanic and they did a pressure test. Leaking intake valve gasket. Replaced, cleaned everything and its running like a champ and no longer running rich.

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