P2135 fault code: throttle position sensor mismatch
Plain-language definition
Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
What does it mean?
On cars with an electronic throttle there's no mechanical link between the accelerator pedal and the throttle: the engine computer reads the pedal's position with sensors and opens and closes the throttle with a small electric motor. For safety, both the throttle body and the pedal usually have two position sensors each (A and B), which measure the same movement independently of each other.
The engine computer constantly compares the voltages of the two sensors; they must agree with each other at all times. If the difference between them goes past a set limit, it stores P2135. The code's definition covers both the throttle and the pedal: on most cars it concerns the sensors in the throttle body, while on some makes it refers to the sensors in the pedal.
Because the engine computer can't tell which sensor to trust, it usually switches to a limp mode that restricts power: the car responds less to the accelerator pedal, accelerates slowly and engine revs may be limited. The check engine light or the electronic throttle warning light may come on; sometimes rough idling or stalling can also occur.
How serious is it?
It's rated Warning, but on many cars it's very noticeable while driving because the engine computer restricts power. Since throttle response can change at an unexpected moment, it's important to find the cause.
Severity is a guide; if the warning light is flashing or you notice symptoms while driving, have the car checked at a workshop.
Common general causes
- Worn position sensors in the throttle body, or a failed throttle body
- A loose connection, corrosion or water getting into the throttle body's or pedal sensor's connector
- Broken wiring, a short circuit or chafing in the sensor wiring
- A problem with the sensors' shared supply (5 V reference) or ground circuit
- Less often, a faulty accelerator pedal unit or engine computer
The list shows general causes; a workshop finds the actual cause on your car with a check.
Definitions by make
Some manufacturers record the same code under their own wording:
- Fiat
- between sensor ped. acc. 1 and sensor ped. acc. 2 Electrical Wiring Fault
- Honda
- Throttle Position (TP) Sensor 1/2 Incorrect Voltage Correlation
- Mitsubishi
- TPS(main/sub) correlation
How does it appear in the 2dakika report?
Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
If the code is read as a confirmed (stored) fault, the report shows it with the "Warning" severity; in pending or past records, codes that don't request the warning light and aren't critical appear as "Info". If the engine computer stored them, the conditions when the fault was recorded (engine temperature, rpm, speed) are shown too.
Read this code with the OBD-X1, and clear it from the app after the repair.
Clearing the code doesn't fix the fault; if the problem persists, the code comes back.