Fuel & air metering · Powertrain · generic (SAE-defined)
P2135: Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation
P2135 means the two throttle position sensor signals, A and B, disagree with each other more than the engine computer allows, so it cannot trust the throttle reading.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P2135 sets
Electronic throttle bodies carry two throttle position (TP) sensors that report the same plate angle in different voltage patterns. The powertrain control module (PCM) constantly compares them, and if their relationship falls outside the expected correlation, P2135 sets and throttle authority is restricted. Correlation limits are manufacturer-specific.
Common causes of P2135
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Worn or failed throttle position sensors in the throttle body
- Corroded or loose throttle body connector
- Damaged wiring or high resistance in a sensor circuit
- Shared reference voltage or ground problem
- Water intrusion into the connector
- PCM fault (uncommon)
P2135 symptoms
- Check engine light and/or reduced power light on
- Limp mode with limited acceleration
- Hesitation or surging
- Stalling or rough idle in some cases
How P2135 is diagnosed
- Scan for all codes and record freeze frame; note reference voltage codes.
- Inspect the throttle body connector and harness for corrosion and spread terminals.
- Graph TP sensor A and B together while slowly moving the throttle (key on, engine off where safe) and look for glitches.
- Check reference voltage and ground at the connector, including voltage drop.
- Wiggle-test the harness while watching live data.
- Replace the throttle body if wiring and power checks pass.
Typical fixes for P2135
- Replace the electronic throttle body (sensors are usually integrated)
- Repair the connector or harness
- Fix a reference voltage or ground fault
- Perform a throttle relearn after repair
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P2135 FAQ
What does code P2135 mean?
P2135 means the two throttle position sensor signals, A and B, disagree with each other more than the engine computer allows, so it cannot trust the throttle reading. The standard definition is "Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation."
Can I drive with a P2135 code?
Limit driving to getting it repaired. Most vehicles respond with reduced power or limp mode, and acceleration may be unpredictable.
Can a wiring problem cause P2135?
Yes. A corroded terminal or a damaged wire can distort one sensor signal and create a mismatch even when the throttle body is fine.
How is P2135 different from P2138?
P2135 compares the throttle body sensors A and B, while P2138 compares the accelerator pedal sensors D and E.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.