OBD-II Code · Sensors
P2135
TPS/APP Sensor A/B Voltage Correlation
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$150–$600
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
The two throttle position sensors don't agree on position.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Severe limp mode
- Reduced power
Likely causes
- Failed TPS moduleMost common
- Wiring issue
- Connector corrosion
Read the full diagnostic procedureP2135 means the two redundant throttle/pedal position sensors aren't correlating with each other — TPS-A and TPS-B at the throttle body should track…
P2135 means the two redundant throttle/pedal position sensors aren't correlating with each other — TPS-A and TPS-B at the throttle body should track in opposite directions through the blade's full range, and APP-D and APP-E at the pedal should do the same. When either pair disagrees by more than the correlation window (usually about 8-10% of full scale for more than 100ms), P2135 sets and the ECM drops to limp mode immediately. This is the most common throttle code on GM full-size trucks and one of the most common across all platforms. The ECM doesn't tell you whether the fault is at the throttle body or the pedal — you have to determine that yourself.
Cheapest-first
- clear the code, then with the engine off and key on, scan-tool the live data and watch all four sensor values simultaneously while you slowly sweep the pedal from rest to full travel.
- APP-D and APP-E should mirror cleanly;
- TPS-A and TPS-B don't move yet (engine off).
- Then start the engine and watch the throttle sensors as the ECM commands blade movement — TPS-A and TPS-B should mirror cleanly.
- Whichever pair shows the dropout, flat-spot, or correlation break is the fault.
Vehicle-specific patterns2007-2014 GM full-size trucks and SUVs (Silverado / Sierra / Tahoe / Yukon / Suburban / Avalanche) with the 5.3L / 6.0L is the absolute textbook P213…
- 2007-2014GM full-size trucks and SUVs (Silverado / Sierra / Tahoe / Yukon / Suburban / Avalanche) with the 5.3L / 6.0L is the absolute textbook P2135 platform — APP-harness corrosion under the driver's-side carpet is so prevalent that GM issued multiple TSBs and many shops keep pedal-assembly pigtails in stock. The fix is repinning the connector or replacing the pedal-side pigtail; full pedal-assembly replacement runs $150-300.
- 2005-2010Pontiac G6 / Saturn Aura with the 3.6L LY7 throws P2135 from internal TPS failure inside the throttle body — full throttle-body replacement required.
- 2008-2013Toyota Sequoia / Tundra 5.7L 3UR-FE sees P2135 from carbon-buildup-induced TPS drift; throttle-body cleaning often resolves it.
- 2010-2014Subaru Forester / Outback 2.5L throws P2135 from a known internal throttle-body TPS fault that was extended-warranty covered on certain VIN ranges. Critical: P2135 is the throttle code where the relearn matters most — after any pedal or throttle-body work on a GM truck, scan-tool the throttle-position-relearn procedure (GDS / Tech 2 / equivalent) or do the key-on / 30-second / key-cycle dance per the FSM; skip it and the correlation window will trip P2135 again within the first drive cycle even with brand-new parts installed.
Look up another code
P2135 — frequently asked
What does a P2135 code mean?
The two throttle position sensors don't agree on position.
What causes a P2135 code?
Common causes: Failed TPS module; Wiring issue; Connector corrosion.
What are the symptoms of a P2135 code?
Typical symptoms: Check engine light; Severe limp mode; Reduced power.
Is it safe to drive with a P2135 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $150-$600.
How do I diagnose a P2135 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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