Is P2135 the EPC light?

On Volkswagen, Audi, Skoda and SEAT models P2135 usually comes with the EPC (Electronic Power Control) light, which covers the electronic throttle system. Other makes show the check engine light, often with a reduced power message. The light only says the throttle system has a fault; the code tells you which part to check.

Can I drive with P2135?

Only gently and only as far as you have to. Many cars cut power hard or hold the engine at a raised idle, so overtaking and joining a motorway become dangerous, and an intermittent fault can return suddenly. Get it checked before any longer journey.

Is P2135 the throttle body or the accelerator pedal?

On most cars P2135 points to the throttle body, because sensors "A" and "B" are the two throttle position sensors inside it. Disagreement between the pedal sensors normally sets P2138. Some makes use the codes differently, so compare the throttle and pedal readings on a reader before buying parts.

Will cleaning the throttle body fix P2135?

Usually not on its own. Cleaning removes carbon from the throttle plate, but P2135 is about the two sensor signals disagreeing, which is most often a worn sensor track, a connector or wiring. Cleaning can help when carbon stops the plate moving smoothly; if the code returns, the throttle body or wiring needs attention.

How much does it cost to fix P2135?

Cleaning and reseating the connector costs nothing to 50 euros. A wiring repair runs 70 to 220 euros, mostly fault-finding time. A new electronic throttle body costs 150 to 600 euros fitted, and a new accelerator pedal assembly 130 to 380 euros. Add 30 to 80 euros where the throttle adaptation needs diagnostic software.

P2135: Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation

Quick Answer

Not safe to drive

P2135 means the engine computer has compared the two sensors it uses to measure throttle opening, sensor "A" and sensor "B", and found that their voltages no longer agree the way they should. On most drive-by-wire cars both sensors sit inside the electronic throttle body, so the usual causes are a worn throttle body, a corroded or loose connector, or damaged wiring; on some makes the code can also point to the accelerator pedal sensors. Because the engine computer cannot tell which signal is right, it normally cuts power into limp mode.

Severity: High · Electrical

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What does P2135 mean?

P2135 is a electrical-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P2135 and illuminates the check engine light.

Where it is on the car

Air filter box
Mass airflow sensor (MAF)
Throttle body and throttle position sensor
Intake manifold and MAP sensor
Engine (cylinder head)

What are the symptoms of P2135?

If your vehicle has triggered P2135, you may notice one or more of these symptoms:

EPC light (on Volkswagen group cars) or check engine light on, often with a reduced power message
Sudden loss of power, sometimes with the engine held at a raised idle whatever you do with the pedal
Accelerator pedal responding late, weakly or not at all
Rough or hunting idle, or stalling when coming to a stop
Cruise control switched off
Fault that comes and goes with bumps or engine heat if the connector or wiring is intermittent

What causes P2135?

Here are the most common causes of P2135:

Worn sensor track inside the electronic throttle body, so one of the two signals drops out or drifts
: high
Corroded, loose or oil-contaminated connector at the throttle body
: high
Chafed or broken wire, or a weak 5 V reference or ground shared by the two sensors
: medium
Faulty accelerator pedal sensor, on makes that report pedal faults under this code
: medium
Low battery voltage or a poor engine ground upsetting the sensor signals
: low
Engine computer fault (rare, check everything else first)
: low

Is it safe to drive with P2135?

No - address this immediately. Not safe for normal driving. When the two throttle position signals disagree, the engine computer cannot be sure how far the throttle is open, so it usually switches to a failsafe: power is cut hard, sometimes to little more than a raised idle. You may be able to creep to a safe place or a nearby workshop, but do not try to overtake, join a motorway or tow a trailer.

How do you diagnose P2135?

Follow these steps to pinpoint the root cause of P2135:

Read all stored codes and the freeze frame. Codes such as P0122, P0123, P0222 or P0223 stored alongside point to the circuit of one sensor, and P2138 points to the accelerator pedal instead. A generic OBD2 reader shows the codes, the freeze frame and, where the engine computer reports them, the standard throttle position and accelerator pedal position readings.
With the ignition on and the engine off, watch both throttle position readings while a helper presses the pedal slowly. The two signals should move smoothly together over the whole travel; a jump, flat spot or dropout in one of them points to the throttle body or its wiring.
Check the battery voltage and the main engine grounds, because low system voltage can make both sensors misbehave at once.
Unplug the throttle body connector and look for corrosion, oil, water and pushed-back pins. Wiggle the harness while watching the readings to catch an intermittent fault.
Back-probe the connector: the 5 V reference should read close to 5 V and the ground close to 0 V. If both are good and one signal is still wrong, the sensor inside the throttle body has failed, and on most cars that means replacing the throttle body as a unit.
After fitting a new throttle body or pedal, run the throttle adaptation. On some makes it is a key-on and idle procedure; on others it needs manufacturer-level software, which a generic OBD2 reader cannot run. Clear the code and road-test.

How much does P2135 cost to fix?

Repair costs for P2135 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Clean and reseat throttle body connector	€0–€10	€0–€40	€0–€50	Easy
Repair throttle body wiring or connector	€10–€40	€60–€180	€70–€220	Moderate
Replace electronic throttle body	€120–€450	€30–€150	€150–€600	Moderate
Replace accelerator pedal assembly (drive-by-wire)	€90–€280	€40–€100	€130–€380	Easy
Throttle adaptation with diagnostic software (where required)	€0–€0	€30–€80	€30–€80	Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

These codes are often seen alongside P2135 or indicate related issues:

Common questions about P2135

What does P2135 mean?: P2135 means the two sensors that measure throttle opening, sensor "A" and sensor "B", are giving voltages that do not agree with each other. On most drive-by-wire cars both sit inside the electronic throttle body and are compared constantly as a safety check. When they disagree, the engine computer cannot be sure how far the throttle is open, so it switches to limp mode.
Is P2135 the EPC light?: On Volkswagen, Audi, Skoda and SEAT models P2135 usually comes with the EPC (Electronic Power Control) light, which covers the electronic throttle system. Other makes show the check engine light, often with a reduced power message. The light only says the throttle system has a fault; the code tells you which part to check.
Can I drive with P2135?: Only gently and only as far as you have to. Many cars cut power hard or hold the engine at a raised idle, so overtaking and joining a motorway become dangerous, and an intermittent fault can return suddenly. Get it checked before any longer journey.
Is P2135 the throttle body or the accelerator pedal?: On most cars P2135 points to the throttle body, because sensors "A" and "B" are the two throttle position sensors inside it. Disagreement between the pedal sensors normally sets P2138. Some makes use the codes differently, so compare the throttle and pedal readings on a reader before buying parts.
Will cleaning the throttle body fix P2135?: Usually not on its own. Cleaning removes carbon from the throttle plate, but P2135 is about the two sensor signals disagreeing, which is most often a worn sensor track, a connector or wiring. Cleaning can help when carbon stops the plate moving smoothly; if the code returns, the throttle body or wiring needs attention.
How much does it cost to fix P2135?: Cleaning and reseating the connector costs nothing to 50 euros. A wiring repair runs 70 to 220 euros, mostly fault-finding time. A new electronic throttle body costs 150 to 600 euros fitted, and a new accelerator pedal assembly 130 to 380 euros. Add 30 to 80 euros where the throttle adaptation needs diagnostic software.

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