P0120: How to Diagnose & Fix — Throttle/Pedal Position Sensor Circuit Malfunction
8 vehicles · 5 makes · $100-$800 repair
How to diagnose and fix P0120: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Renault Megane · 2003–2023
The Megane displays an "Injection Fault" warning on the dashboard, which can be triggered by numerous sensors and components. Common causes include the crankshaft position sensor, throttle body, and fuel pressure regulator.
Common Symptoms
- Injection fault warning
- Engine stalling
- Difficult starting
- Loss of power
How to Fix
Diagnose with Renault CLIP or compatible diagnostic tool to identify the specific fault code. Common fixes include crankshaft sensor replacement, throttle body cleaning, and fuel pressure regulator replacement.
Sources for this issue (1)
Volvo V40 · 2000–2004
The S40/V40 first generation (2000-2004) uses the same problematic ETM as other Volvos of the era. Internal contact wear causes throttle position sensor errors and reduced power mode.
Common Symptoms
- Reduced power mode
- Check engine light
- Stalling
- Rough idle
How to Fix
Confirm ETM failure by scanning for throttle-related DTCs such as ECM-91A7/91B7 or generic P0121, P0221, and by checking live throttle angle signals for dropouts or mismatch between the internal position sensors. On the 2000-2004 V40, the fix is typically replacement of the Magneti Marelli electronic throttle module with an updated/rebuilt unit, followed by throttle adaptation/software initialization with Volvo VIDA or equivalent; inspect and clean the throttle body connector and wiring at the same time. If the car has severe idle instability or stalling, do not rely on cleaning alone, because worn internal contact tracks usually return quickly. Typical repair cost is about $500-$900 using a quality rebuilt ETM and adaptation, or $900-$1,400 with a new OEM unit and dealer programming.
Volvo S70 · 1999–2000
The S70 ETM (drive-by-wire throttle body) develops internal contact wear causing intermittent stalling, reduced power mode, and check engine light. This was subject to a Volvo extended warranty and is one of the most common P2 platform failures.
Common Symptoms
- Reduced power mode
- Stalling
- Check engine light
- Rough idle
- Throttle not responding
How to Fix
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- XeMODeX VO.1020 pre-programmed contactless Volvo electronic throttle module
replace a scan-data-confirmed internal S70 ETM sensor failure with a VIN-preprogrammed contactless unit Fitment/availability: 1999-2000 Volvo S70 Turbo and non-turbo Magneti Marelli electronic-throttle branch; VIN and original-module det…
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Volvo V70 · 1999–2002
Volvo C70 · 1999–2005
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P0120 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0120 mean?
P0120 stands for "Throttle/Pedal Position Sensor Circuit Malfunction." This code indicates a malfunction in the throttle position or accelerator pedal position sensor circuit. These sensors tell the computer how far the throttle plate is open or how far you've pressed the pedal, which the computer uses to control engine power and, on drive-by-wire systems, the throttle itself. When the signal is out of range, erratic, or doesn't make sense relative to other inputs, P0120 sets. Symptoms can include hesitation, surging, stalling, or the vehicle entering a reduced-power 'limp' mode for safety.
What are the most common causes of P0120?
The most common causes of P0120 are: Failed throttle position sensor, Corroded or loose TPS/pedal sensor connector, Damaged or shorted sensor wiring, Carbon buildup or a sticking throttle body, Worn throttle body or throttle plate, Poor sensor reference voltage or ground, Faulty accelerator pedal position sensor, Faulty PCM/ECM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0120?
Repair costs for P0120 range from $100 to $800, depending on the vehicle and root cause.
Which vehicles are affected by P0120?
Au7o has documented P0120 across 8 vehicle models from 5 manufacturers: Chevrolet, GMC, Renault, Toyota, Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.