P0122 means the ECU is seeing an abnormally low voltage on throttle position sensor circuit A, typically under 0.2V when it expects 0.5V to 4.5V. Most cars drop into limp mode with capped throttle.
Scan your own car in about 60 seconds: see whether P0122 is really what it has, how urgent it is, and what the fix should cost. Free on iPhone and Android, on any ELM327 adapter.
Get Skanyx freeP0122 means the ECU is seeing an abnormally low voltage on throttle position sensor circuit A, typically under 0.2V when it expects 0.5V to 4.5V. Most cars drop into limp mode with capped throttle.
P0122 is a electrical-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0122 and illuminates the check engine light.
If your vehicle has triggered P0122, you may notice one or more of these symptoms:
Here are the most common causes of P0122:
No - address this immediately. The ECU usually forces the car into limp mode with reduced power and a locked idle. You can limp home, but hard acceleration and highway merging become risky.
Follow these steps to pinpoint the root cause of P0122:
Repair costs for P0122 vary depending on the root cause and your vehicle. Here are typical estimates:
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0122 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
The EPC light comes on with P0122 on these Golfs. On 1.4 TSI engines the throttle body actuator motor brushes wear out around 120,000 to 180,000 km. VW part 03C 133 062 is the common replacement.
The TPS is integrated into the throttle body (Toyota part 22030-0H030 range) and not sold separately. Toyota's service procedure requires an idle air volume learn after replacement or battery disconnect.
BMW uses dual redundant TPS in both the pedal and throttle actuator. P0122 usually pairs with P2135 and drops the car into a restrictive failsafe. Water leaks into the E-box under the cowl are a well-documented cause on E90s.
These codes are often seen alongside P0122 or indicate related issues:
You can move the car short distances, but limp mode caps power and makes merging or overtaking dangerous. Fix it before any highway driving.
It'll clear the light, but if the sensor or wiring is faulty the code returns within minutes of driving. You're masking the problem, not fixing it.
Yes, on almost every drive-by-wire vehicle. Without the relearn the idle will hunt or stall. Most OBD2 apps with bidirectional control can run it in under a minute.
The connector probably wasn't fully seated, or carb cleaner seeped into the TPS. Reseat the plug and let it dry overnight before condemning parts.
Yes. If system voltage drops below about 10V during cranking or under load, the 5V reference can sag and log a low-input code. Load-test the battery before chasing sensors.
A 15 euro Bluetooth adapter and a free phone app read the exact fault code a shop charges 30 to 100 euros to pull. Here is how to do it yourself in 5 minutes.
A failing throttle body shows up as a hunting idle, stalling, hesitation or limp mode. What the part does, the symptoms, the codes, and the repair cost.
The Reduced Engine Power message is the ECU cutting throttle to protect itself. Here is what triggers it, whether you can drive, and what the fix costs.
Clean a sooty throttle body in under an hour for around 15 euros, handle the idle-relearn question honestly, and verify the fix with OBD2 live data.
A flashing check engine light means the engine is misfiring right now. Pull over and read the code: the fix is usually $80 to $400, the delay costs $1,500 up.
An unfamiliar symbol just lit up and you need to know whether to stop. Read the colour first, then find your symbol in the table: every one carries its verdict.
Your car logged P0122. Skanyx reads it on any standard Bluetooth OBD2 adapter, tells you whether it is safe to keep driving, and breaks down the likely repair so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.
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