2003 Cavalier 2.2l How to fix Code P0171?

(2011-08-04 14:20:11)

1. George n Barbara Says: Car stumbles when driving. Codes comes up P0171 and no other codes. Recently had new fuel pump and filter, fuel injection cleaning, new o2 sensors, IAC, Temp sensor, map sensor, plugs and throttle body. Only has 95k miles. This does not have a PCV. Had several mechanics work on it and none fixed the problem, just replaced everything with no results. They all said they checked for vacuum leaks, but found none. They are all baffled?

2. REV B Says: Have someone put a fuel pressure gauge on it and check the pressure. Since you changed about everything on it, my guess is the fuel pressure regulator is bad. You can check for vacuum leaks yourself by spraying carb cleaner around the intake manifold while it's running. If it immediately idles up or down, it's a bad intake gasket. On some vehicles, it's the MAF sensor that is bad. Since your vehicle doesn't have a MAF, I ruled that out as a possible cause. If any of your mechanics said it's MAF related, leave immediately because they aren't familiars with 2003 Cavaliers.

3. REV B Says: If you need more answers, I would be glad to help. I have a car repair ministry and Chevrolet's are my specialty.

4. Lkn4trouble Says: Try cleaning the MAF, make sure there are no air leaks after the MAF. use mechanical fuel pressure gauge to check fuel pressure. Most of the time system to lean codes are O2 related or MAF related.

5. Ken D Says: http://www.engine-light-help.com/P0171-check-engine-light.html
causes. The following is an overview of P0171 check engine light code possible causes.

Fuel System:

Leaking or faulty fuel pressure regulator
Plugged or dirty fuel filter or lines
Fuel pump weak or defective check valve
Injectors leaking or faulty
Low fuel pressure or running out of fuel
Leaking EVAP system components
Faulty FRP (Fuel Rail Pressure Sensor)

Air Intake System

Vacuum leaks
Contaminated, damaged or faulty Mass Air Flow sensor
PCV valve leak or stuck open
Air induction turbulance caused by wrong filter
Oil dipstick not seated
Air leaks after the Mass Air Flow Sensor (MAF)
Oil coated aftermarket air filter

Exhaust System

Any exhaust leak before or near the oxygen sensors

EGR System

Vacuum line disconnected from EGR System Module (ESM)
EGR valve, tube or gasket leak
EGR vacuum regulator valve leaking

Secondary Air Injection System

Mechanically stuck secondary air injection valve