Question about 2003 Chevrolet Avalanche

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Check engine light keeps coming on. Its giving me a code p0171.

I put a new (Jegs) Mass Air Flow sensor in last year. I just clean it and the K&N air filter two weeks ago. Check engine light came back on today. What should i check next?

Thanks,

Steve

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  • Anonymous Jan 13, 2009

    replaced MAF sensor p0101 ,p0171,p0174 comes up.came up before i replaced the MAF sensor also has rough idle most of the time.some times it idles good 1out of 10 times i stop at a light.

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Have them check the catalytic converter.

Posted on Apr 15, 2009

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Replace your gas cap.

Posted on Aug 04, 2008

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I have a 2005 mercury Monterey van with a check engine light on. Autozone diagnosed either a mass air flow sensor or O2 sensor problem. I tried cleaning the air flow sensor with air flow sensor cleaner but...


If it is running lean, I'd check correct fuel pressure. Then check for a vacuum leak. 02 sensors are part of a tune-up. I don't like to replace parts unless I'm sure.

I can't rule out a maf sensor.

Jul 29, 2014 | 2005 Mercury Monterey

1 Answer

ISUZU TROOPER 3.2 V6 CODE P0101


P0101 ISUZU - Mass Air Flow Circuit Performancexicon.jpghttp://engine-codes.com/p0101_isuzu.htmlForum CodePossible causes- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
- Intake air leaks
- Faulty mass air flow sensor
Tech notes Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor

Jul 04, 2012 | 2001 Isuzu Trooper

2 Answers

Check engine light on; engine codes P0171 and P0174


p0171 is lean exhaust bank one ( passenger side) and p0174 is lean exhaust bank 2 ( drivers side). First we need to look for vacuum leaks, low fuel pressure, Intake air leaks after the mass air flow sensor, pvc system. Because you have both sides lean I would start looking at these spots.

May 23, 2011 | 1998 Ford F150 Regular Cab

1 Answer

Keeps giving P0171 reading any help


P0171- System Too Lean (Bank 1)

The adaptive fuel strategy in the vehicle's computer constantly monitors the fuel delivery system to make sure the engine is running at an optimum air to fuel ratio, which is 14.7:1. The computer adjusts injector pulse width to regulate the amount of fuel going into the engine. The oxygen sensors relay information to the Powertrain Control Module (computer), informing it of the oxygen content in the exhaust. This information is translated by the computer, and used to determine if more or less fuel is needed. The computer will then adjust fuel flow (and possibly other related engine operating characteristics), to keep the correct air fuel mixture. This loop continues as long as the engine is running.

A P0171 check engine light code is set when the computer has reached a rich calibration limit and can not add enough fuel to maintain the correct mixture.

Possible 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

Diagnostic Help:
A very thorough discussion of how to approach and repair a P0171 check engine light code can be found here. If you need further assistance let us know. Please be sure to stop back in and visit some of our other very useful site features to lear more about your car's emissions system.

Hope this helps (remember to rate this answer).

Jan 22, 2011 | 2000 Volkswagen Beetle

2 Answers

Code 171 and engine light is on


--BANK 1 = DTCs P0171 (lean) and P0172 (rich)

-Check intake air system for leaks, obstructions and damage.
-Check air cleaner element, air cleaner housing for blockage.
-Verify integrity of the PCV system.
-Check for vacuum leaks.

I would try cleaning the Mass Airflow Sensor first. A dirty Mass Airflow Sensor is a common problem for triggering PO 171 & 174 codes.

Good luck and keep me posted.

Oct 21, 2009 | Chevrolet Colorado Cars & Trucks

1 Answer

Volvo S40 2.0T (2000 X Reg) P0102 P0171


Hi, Since you have both codes Fuel system lean and MAF low I would bet money on that you have an intake air leak after the throttle. Check all hoses connected to the intake manifold, gaskets, injectors are put in place etc.

Aug 22, 2009 | Volvo S40 Cars & Trucks

1 Answer

Check engine light is on


There are many causes to this problem, but you might need to take it to a shop to find the real problem.
Here's everything I know about it.
P0171 System too Lean (Bank 1)
How does a P0171 code trigger the check engine
light? This code will trigger the check engine light as follows:

The adaptive fuel strategy in the vehicle's computer constantly monitors the fuel delivery system to make sure the engine is running at an optimum air to fuel ratio, which is 14.7:1. The computer adjusts injector pulse width to regulate the amount of fuel going into the engine. The oxygen sensors relay information to the Powertrain Computer Module (computer), informing it of the oxygen content in the exhaust. This information is translated by the computer, and used to determine if more or less fuel is needed. The computer will then adjust fuel flow (and possibly other related engine operating characteristics), to keep the correct air fuel mixture. This loop continues as long as the engine is running.

A P0171 check engine light code is set when the computer has reached a rich calibration limit and can not add enough fuel to maintain the correct mixture.

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 turbulence 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

Apr 12, 2009 | 2000 Hyundai Sonata

1 Answer

Cleaning the Mass Air Flow Sensor


i will try to help. 171/174 indicates lean condition in engine. the mass air flow sensor is located in the rubber tube going to throttlebody. you can try to clean it. using mild carb cleaner safe for sensors, remove sensor from tube. spray clean the tiny wires located in the cylinder. do not touch them, they are very delicate. these engines are also notorious for leaking intake gaskets and faulty pcv valves. these will all set these 2 codes. feel free with anymore questions.

Nov 15, 2008 | 2004 Ford Freestar

3 Answers

Mass Air Flow Sensor, oxygen sensor and coil plugs


look for vacuum leaks the last 4 codes are lean codes
primarily lookm at the pcv hose noturious for collapsing

Sep 16, 2008 | 2000 Ford Expedition

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