Question about 2003 Chevrolet TrailBlazer

2 Answers

P0172 and P0128 Error Code 2003 Trailblazer 4WD

I am reading an error code P0172 System too rich (Bank 1) and P0128 Cooland Thermostat (coolant temperature below thermostat regulator temp). The engine appears to idle and run fine; however, the service engine soon light continues to alternate on and off. I have an inline 6 engine on a 2003 Trailblazer LT 4WD. The engine has just over 112k miles.

The fan clutch is clicking while attempting to engage. I believe I need to replace the fan clutch and based on error P0128, a new thermostat.

Any additional suggestions

Posted by on

  • 2 more comments 
  • rburnsc Feb 11, 2009

    I went to get my 03 trailblazer inspected. Failed because of an error code to do with my thermostat. I appreciate the advise about the O2 sensor in case this does not fix the problem. Now I have to figure out how to get to the thermostat.

  • Anonymous Mar 16, 2009

    diagnosed with code ? for T-stat. Replaced T-stat, however, service engine light still coming on. Brought to a different Chevy dealer and diagnosed the same. Tech had to "relearn" t-stat for it was not set properly. Service engine light intermittent. Seems to do better in warm weather. Temp gage varies/fluctates during driving. Will reach approximately 210 on warm days and the light goes off. Previous tech has suggessted a cam phaser change though not sure if this will cause the light to stay off.

  • Anonymous Mar 18, 2009

    Same exact problem with my 04 Envoy.

  • Anonymous Apr 01, 2014

    clutch wont engage even when the engine is up totemperature

×

2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    President:

    An expert whose answer got voted for 500 times.

  • Master
  • 362 Answers

PO172 means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). I would replace the thermostat first. The computer could be injecting too much fuel because it thinks it never gets to operating temperature. That may keep the light off.

Posted on Jan 28, 2009

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    President:

    An expert whose answer got voted for 500 times.

  • Master
  • 1,201 Answers

The po172 is the 02 sensor, replace that. I would change the thermostat first, before the fan clutch and see if it is still doing it, then go after the fan clutch.

Posted on Jan 28, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

P0172 2003 trailblazer


P0172 states that the "bank 1" side of the engine is running too rich.
Here is a link explaining it in more detail and giving possible causes and solutions.


http://www.obd-codes.com/p0172

Apr 14, 2015 | 2003 Chevrolet TrailBlazer

1 Answer

4 Codes in computer


code p0128 indicates a mechanical fault ( could be the thermostat stuck open)
code p0174 -system too lean -bank2 ===causes --intake /exhaust leak--fuel pressure/pump--injectors--AIR system--hose connection/s
code po171 refers to system too lean bank 1 same as po174 with the HO2S sensor being the culprit. As to all being related . only by way of the o2 sensors
code p0442 is not connected to the first 3 as it is in a different section of the fuel system

Apr 09, 2014 | 2003 Saturn VUE

1 Answer

Light check engine obd p0172


Error Code: P0172
Fault Location:
Fuel Trim, System too Rich, Bank 1
Possible Cause:
Evaporation emission (EVAP) canister purge valve.
Fuel pressure.
Fuel Injector(s).
Heated oxygen sensor (HO2S).
Mass air flow sensor.
Engine coolant temperature sensor.
Element air cleaner, clogged.

Dec 08, 2013 | Toyota ECHO Cars & Trucks

1 Answer

2004 trailblazer code po128


P0128:
P0128 OBD-II Trouble Code
Technical DescriptionCoolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

What does that mean?This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125

In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.

CausesA code P0128 may mean that one or more of the following has happened:

Low engine coolant level .
Leaking or stuck open thermostat .
Faulty cooling fan (running too much) .
Faulty coolant temperature (ECT) sensor.
Faulty intake air temperature (IAT) sensor .Here's a link on replacing your thermostat.

Feb 06, 2013 | 2004 Chevrolet TrailBlazer

1 Answer

What's your problem?error code 0128


DTC P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125

In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle. If have other request, just contact us about OBD Diagnostic Truble Codes.

Hope this helps.

Oct 03, 2011 | 2003 Chevrolet TrailBlazer

1 Answer

I was told I failed the NY inspection test due to error codes po172 and po300. What do these indicate is wrong and where the problem may be??


p0300 is code for miltible misfires. The p0172 is code for a rich reading from engine bank #1, this code may be set by the misfireing causing raw fuel to exit that bank to the sensor in the exhaust system. The most common cause is spark related, spark plugs, wires, dist. cap. etc. A less common cause is with the fuel injection system.

Jun 24, 2011 | 1996 GMC Yukon

1 Answer

2002 dodge durango 4.7L SLT Plus with lack of power with service engine light on and p0172 error code


error code P0172: system too rich(bank 1)
In my opinion, replace the oxygen sensor.

Dec 13, 2010 | Dodge Durango Cars & Trucks

1 Answer

What do codes P0128, P0133, P0496


Definition of Diagnostic Trouble Code P0128 Category Powertrain Definition Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
Definition of Diagnostic Trouble Code P0133 Category Powertrain Definition O2 Sensor Circuit Slow Response Bank 1 Sensor 1

Definition of Diagnostic Trouble Code P0496 Category Powertrain Definition Evaporative Emission System High Purge Flow

Mar 10, 2010 | 2006 Suzuki Forenza

2 Answers

5 error cods on my 2002 Jetta GLS 1.8 Turbo Engine


P0420= Catalyst System Efficiency Below Threshold Bank 1
P0300=Random/Multiple Cylinder Misfire Detected
P0301=Cylinder 1 Misfire Detected
P0172=System Too Rich Bank 1
P2181=Cooling System Performance
you need to write these down,have someone clear the codes in the car,then go for short ride and recheck which if any code reappears.it's like domino's affect,one sensor can start a chain affect with the others.

Dec 09, 2009 | 1998 Volkswagen Jetta

Not finding what you are looking for?
2003 Chevrolet TrailBlazer Logo

3,952 people viewed this question

Ask a Question

Usually answered in minutes!

Top Chevrolet Experts

yadayada
yadayada

Level 3 Expert

60792 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

21949 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

6811 Answers

Are you a Chevrolet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...