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2010 Chevrolet Silverado 5.3L LC9: P0122, P0223, P2135, C0242, U2100 - Limp Mode & Traction Control Failure After Replacing Throttle Components

Model: 2010 Silverado Fault Code: C0242 Posted: 2016-01-30 11:44

My 2010 Chevrolet Silverado with a 5.3L LC9 engine is repeatedly entering limp mode and displaying 'Engine power reduced' and 'Service traction control'. The diagnostic trouble codes (DTCs) are P0122, P0223, P2135, C0242 (PCM indicates traction control system malfunction), and U2100 (CAN Bus communication failure). I've conducted extensive research and replaced all commonly recommended components: the throttle body sensor (TPS) actuator/motor, the pigtail connector to the TPS, and the accelerator pedal with its integrated sensor. Each replacement initially improved performance for a short period before the issue returned. After replacing both the accelerator pedal and its associated sensor, the truck responded more smoothly to pedal input. However, the limp mode and DTCs persist. The throttle body itself appears mechanically functional and has not been replaced. The presence of U2100 (CAN Bus communication error) suggests a potential issue with vehicle network communication—possibly related to the Engine Control Module (ECM). Given that live data from my Snap-on Ethos+ scanner shows normal values during operation, I suspect the problem may be intermittent or software-related. I've checked dealer service bulletin 11273B — 'Special Coverage Adjustment – Throttle Position Sensor Replacement'—which mandates replacement of the TPS and reprogramming of the ECM. While this repair is covered under warranty for 10 years or 120,000 miles (whichever comes first), my truck has exceeded that threshold. I'm now seeking advice on whether a faulty ECM, corrupted software, or another underlying issue could be responsible. Any insights into troubleshooting these codes—especially C0242 and U2100—are greatly appreciated.

Related fault codes
C0242P0122P0223P2135U2100
Comments (8)
Anonymous 2016-01-30 12:54

Is the vehicle stock? No aftermarket modifications or added components (e.g., performance parts, custom wiring)? What engine model is it specifically?

Anonymous 2016-01-30 13:00

All replaced parts are OEM AC Delco components. Engine is a 5.3L LC9. The only non-stock modifications are 1-inch wheel spacers and a K&N air intake.

Anonymous 2016-01-30 14:06

Check with your dealer about service bulletin 11273B — 'Special Coverage Adjustment – Throttle Position Sensor Replacement'. It requires replacement of the throttle position sensor and reprogramming of the Engine Control Module (ECM). The repair is free under warranty for 10 years or 120,000 miles from original service date, regardless of ownership.

Anonymous 2016-01-30 14:32

My truck has surpassed 120,000 miles and is no longer covered by manufacturer warranty. Are there any reliable aftermarket solutions or diagnostic steps I can take?

Anonymous 2016-01-30 14:44

kev2 wrote: Service bulletin 11273B — 'Special Coverage Adjustment – Throttle Position Sensor Replacement' requires TPS and ECM reprogramming. The repair is free under warranty for 10 years or 120,000 miles from original service date. I have already replaced the accelerator pedal sensor, throttle position sensor (TPS), and its pigtail connector.

Anonymous 2016-01-30 14:48

Apologies—both the TPS, accelerator pedal, and associated pigtail have been fully replaced. Since the vehicle now shows a CAN Bus error (U2100), I'm beginning to suspect a failing or miscommunicating ECM.

Anonymous 2016-01-30 14:59

The key point in the bulletin is 'REPROGRAM'—was this reflash performed? The dealer offered free service under warranty, but being past 120k doesn't mean it's not still necessary. Especially for ECM reprogramming, which may resolve communication issues like U2100 and C0242. I'm having difficulty finding a reliable DIY diagnostic tool or test procedure for these codes—most sources require professional-grade scanners.

Anonymous 2016-01-30 15:07

I used a Snap-on Ethos+ scanner. During live data monitoring, all parameters appear normal. The issue manifests as intermittent limp mode and returns to normal after a short time. After the initial TPS reflash, no improvement occurred. I then replaced the pigtail and accelerator pedal—no change in behavior. I don't see any reason to repeat these steps unless there's a deeper software or hardware root cause.