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Old 02-15-2015, 05:12 AM   #1
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Default System too lean gmc envoy 05

Hi

I have this code

P0171 system too lean
P0420
P1131

P0171 and p0420 are pending .

The fuel pressure is correct . Start with what ?
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Old 02-15-2015, 09:01 AM   #2
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i think if it was me i would make sure the power is right to the o2'*. then replace the o2s. sometimes the heater goes bad and if the car hasent had the o2s replaced could help as a maintenance item. could still have a bad cat but thats not real easy to check.
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Old 02-15-2015, 10:27 AM   #3
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If it was the O2'*, they would set codes, especially for the heater circuit.....and it has, it has set P1131.....could also be a vac leak....restricted injector(*).........exhaust leak before O2 sensor....harness problem ....

This engine may have 3 or 4 injectors...this code is for the pre O2 sensor on #1 cylinder bank....

P0420, is usually a cat....is there a lack of power during hard acceleration?

So, if there are no outside factors affecting the O2 sensor, as JW suggested, this might be your problem, especially on a 10 year old vehicle....
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Old 02-15-2015, 10:39 AM   #4
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Thanx ..

There is no vac leak .. The car is little hard at high rpm
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