2003 silverado 1500 Check Engine Light

**ChevyFarmKid** · 03-01-2009, 12:23 PM

On my 03' Silverado 1500 with a 5.3 liter, my check engine light is coming on and kicking out 2 codes, p0171 and p0174. I have already put a new mass air plow sensor in, What next?

**doddelectric** · 02-16-2011, 11:21 PM

i have a 2003 4x4 4.8 i am having the same problem ! if any one has the solution please let us know

**COLIN DE** · 02-17-2011, 06:31 AM

If the light comes back on after sometime then go to either autozone (US) or parts source(Canada) and ask them to hook up your car to their portable code scanner (this is usually a free service). Once the scanner tells you the code, google it and then you would know the problem.

**mfleetwood** · 02-17-2011, 05:05 PM

Originally Posted by doddelectric

i have a 2003 4x4 4.8 i am having the same problem ! if any one has the solution please let us know

P0171/P0174 A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky(use a fuel pressure gauge to check fuel pressure at idle)

* Dirty (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

**doddelectric** · 02-22-2011, 03:11 AM

HOW much pressure should i have at idle on fuel pump

**cshoule** · 02-24-2011, 11:50 PM

I've seen this before, the one i worked on gave simular codes, all along it was the harness at the front of the intake.the cover will have to be taken off to see. a wire came off the pin at bulkhead plugin on that one. a vortec should have around 60psi of fuel pressure.