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
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.
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.
4,443 views
Usually answered in minutes!
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.
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.
Same exact problem with my 04 Envoy.
clutch wont engage even when the engine is up totemperature
×