What could cause code PO128 to come up on a 2002 Chevy Trailblazer

the t/b and envoys have known trans problems 1 is torque converter other is sun gear /basket failure --the diesel would cause rough and some performance issues but not really tranny problems have vehicle scanned for trouble codes also the 4x4 module causes headaches such as going into neutral or 4x4 on its own

Ull need to scanit w a factorytool at a privateshop. It reads a datastream to pinpoint issues. Those portabl readers are general. Dont just replaceparts n hope. Oldercars can hav worn wireharness causin weird problms too. Unplug computer n cleanpins..dirt is common in aging vehicles creating issues. Since its jyst an emmission thing udont need to worry its runnin too lean or sumthin crucial

First you need to have EBCM - electronic brake control module check for DTC'S - diagnostic trouble code's . If the light is on there is a code stored . I think most part stores can do this and for free . After you find out what code is stored , looking up that code in service repair information for diagnostic trouble shooting chart would be next step . There are a few codes too.
DTC C0035 or C0040
DTC C0045 or C0050
DTC C0110
DTC C0131
DTC C0161
DTC C0186
DTC C0196
DTC C0201
DTC C0240
DTC C0241 or P0856
DTC C0244 or P1689
DTC C0245
DTC C0283
DTC C0287
DTC C0290 or C0292
DTC C0455
DTC C0550
DTC C0558

Find the code do the diagnostic's , fix the problem , wiring issue's , a sensor , bad module ,what ever it is . The light will go out then . Here is a sample of code discription .
• DTC C0035 Left Front Wheel Speed Sensor Circuit
• DTC C0040 Right Front Wheel Speed Sensor Circuit

code p0014 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

forums.trailvoy.com > ... > OEM Issues

Sep 8, 2007 - 11 posts - ‎8 authors
On my Trailblazer I have a code P0014 . this says Camshaft Position Actuator B ... If the desired and actual cam phase angle error exceeds its ... This diagnostic procedure supports the following DTC: ... replace the camshaft actuator solenoid, change the engine oil and filter, ... 2004 Chevy TrailBlazer LT P0014 - Camshaft Position Actuator Solenoid "Relearn"
11 posts
Dec 11, 2009
cam crank sensor mismatch
11 posts
Jul 4, 2009
More results from forums.trailvoy.com

Tech Code "dtc P0014" 2003 Trailblazer - Chevy S-10/Blazer ...

www.gm-trucks.com/.../72278-tech-code-dtc-p0014-2003-trailblazer/

Dec 31, 2007 - 14 posts - ‎6 authors
Tech Code "dtc P0014" 2003 Trailblazer - posted in Chevy ... it had been serviced before for the same thing in 2003 or 2004! ... replace the camshaft actuator solenoid, change the engine oil and .... The extended war. co. prob. would not be to happy since they already fixed the sensor once or twice already.

Replace a Camshaft Position Actuator Solenoid Valve on a ...

? 8:05
https://www.youtube.com/watch?v=4Dkdd287AKg

code p0132 refers to heated oxygen sensor (HO2S) 1 bank 1 --low voltage===causes --wiring short to positive---HO2S sensor---ECM
replace the sensor using the correct socket so that the new sensor wires are not damaged during the fitting.

Possible causes
- Faulty Engine Control Module (ECM)
- ECM harness is open or shorted
- ECM circuit poor electrical connection

Read more: http://engine-codes.com/u0100_chevrolet.html#ixzz3BpsbZ5mr

This code indicates a rich mixture is being detected. This can be caused by a number of things, such as excessive fuel pressure, vacuum leak, bad O2 sensor, saturated Evap canister.

2002 Chevy trailblazer was put on machine and had codes U1041-P1633 and P0014 stored in ECM What does this mean

The vehicle should have a stored trouble code, go to an Auto Zone they will read the code for free. Usually idles surges are caused by a malfunctioning TPS sensor or throttle position sensor.

The code indicates an issue with the Throttle Actuator control. This is a little motor on the throttle body that opens the throttle plates at idle. That control motor may be bad and thus, causing a low idle.

I hope this helps.