P0120: How to Diagnose & Fix — Throttle/Pedal Position Sensor Circuit Malfunction
6 vehicles · 4 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 (2)
GMC Terrain · 2010–2017
First-generation Terrains (2010-2017) are prone to a sudden 'Reduced Engine Power' warning caused by a failing electronic throttle body. Carbon and grime build up inside the bore and the internal throttle position sensor (TPS) fails or reads erratically, causing the ECM to enter a limp/reduced-power mode that limits the vehicle to very low speed. This is a widely reported failure on the naturally aspirated 2.4L four-cylinder and 3.6L V6 engines and frequently appears alongside a 'Service StabiliTrak' message. The most commonly cited trouble code is P2135 (throttle/pedal position sensor voltage correlation). No NHTSA recall covers the throttle body; it is addressed through non-recall repair.
Common Symptoms
- 'Reduced Engine Power' message on dash
- Sudden loss of acceleration / limp mode
- Check engine light
- 'Service StabiliTrak' message
- Rough idle or stalling
How to Fix
Clean the throttle body if carbon buildup is the cause; if the throttle position sensor has failed the electronic throttle body assembly is replaced as a unit and the idle/throttle relearn procedure is performed.
Sources for this issue (2)
Volvo C70 · 1999–2005
This is the same ETM failure as on the S70/V70/S80/S60 Volvos of the same era (the first-gen C70 shares the P80 platform with the 850/S70). The first-generation C70 (1999-2005) is most susceptible.
Common Symptoms
- Reduced power mode
- Stalling
- Check engine light
How to Fix
Confirm ETM failure by scanning for throttle-related DTCs such as P0121, P0221, P2135, or limp-home faults, then use live data to verify erratic throttle angle signals and inspect the ETM connector and wiring before condemning the unit. On 1999-2001 C70 models, the usual fix is replacement of the original Magneti Marelli electronic throttle module with the updated Volvo unit or a professionally rebuilt contactless-sensor ETM, followed by a software download and throttle adaptation with Volvo's dealer diagnostic tool (VIDA/DiCE). Clean the throttle bore only if carbon buildup is minor; cleaning will not repair worn internal position sensors. Typical repair cost is about $700-$1,400 depending on whether a new OEM ETM, rebuilt unit, and dealer software reload are required.
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 ETM sensor failure with a VIN-preprogrammed contactless unit Fitment/availability: 1999-2004 Volvo C70 Turbo ME7 electronic-throttle branch; VIN and original module information are required for pre-…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (4)
Volvo V70 · 1999–2002
Volvo S70 · 1999–2000
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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 6 vehicle models from 4 manufacturers: Chevrolet, GMC, Renault, Volvo.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.