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2003 Chevrolet Suburban 4x4 with 6.0L V8: Persistent P2135 Code After Multiple Repairs

Model: 2003 chevrolet suburban 4 Fault Code: P2135 Posted: 2017-08-14 15:41

I've been struggling with the P2139 code (corrected to P2135) on my 2003 Chevrolet Suburban 4x4 equipped with a 6.0L V8 engine for several years. I've already replaced the throttle body, cleaned it thoroughly, and swapped out the throttle position sensor. More recently, I replaced the entire accelerator pedal assembly including its position sensor (APP), yet the P2135 code continues to appear. I'm hesitant to replace the ECM as it's a costly option, but the persistent nature of this fault suggests it may be the root cause. Local dealerships recommend bringing the vehicle in for diagnosis, which often results in high repair bills due to extensive part replacements without clear resolution. Is there a known reset procedure or diagnostic protocol that I'm missing? I currently use an OBD-II scanner, but it lacks depth—especially live voltage readings and real-time data graphing. When attempting to clear the code, it returns within minutes. I suspect deeper diagnostics are needed to identify whether the issue lies in sensor feedback, wiring, or a control module failure. Are there professional-grade scanners available that can display live voltages, monitor multiple sensors simultaneously, and generate graphs for analysis? Any recommendations would be greatly appreciated. Thanks, Jciwolf

Related fault codes

P2135

Comments (4)

Anonymous 2017-08-15 09:00

The diagnostic capability of a scanner is directly tied to its price. Professional-grade scanners provide live sensor data and real-time graphing, which are essential for diagnosing complex issues like P2135. Also, check for Technical Service Bulletins (TSBs)—specifically TSB #03-06-04-062—related to this vehicle and code.

Anonymous 2017-08-15 16:23

I've completed all DMM (digital multimeter) tests on ignition systems and motor resistance. I also performed a 'running back' wire test with no abnormalities found. The only remaining component is the pedal module. During testing, when a friend slowly moves the pedal up and down, I observe no voltage anomalies in the signal or power wires. The P2135 code persists regardless of operation. Interestingly, if the vehicle is restarted and left to idle, the check engine light clears until the accelerator pedal is pressed—this behavior is puzzling. This may indicate a delayed sensor response or communication issue between modules. I'm seeking a scanner that can read live voltages and graph sensor data over time. While expensive, such tools might offer better insight than replacing parts that don't resolve the problem. Thanks, Kev2

Anonymous 2017-08-15 16:48

A quick clarification: the throttle position sensor (TPS) and pedal position sensor (APP) are distinct components. The P2135 code often relates to a mismatch between TP1 and TP2 signals, which may stem from improper calibration or faulty communication. Professional scanners allow multi-sensor monitoring and real-time graphing—tools like CaChing offer this functionality. Have you reviewed the freeze frame data associated with the P2135 event? This could reveal critical timing or voltage anomalies. I’ll send you a copy of TSB #03-06-04-062 tomorrow. Also, confirm that no other diagnostic codes are present—only P2135?

Anonymous 2017-08-15 17:15

Regarding the pedal vs throttle body confusion: I've worked on both systems. My initial issue was with the throttle body, which I completely replaced with a new sensor assembly. Since then, I’ve encountered APP-related codes and a power reduction warning message. After replacing the full accelerator pedal assembly—including the actuator and position sensor—the P2135 code still appears. This strongly suggests either a deeper software issue or a hardware failure in the control module. Thanks, Kev2