Throttle/Pedal Position Sensor A Circuit Low Input
The P0122 code means the vehicle's onboard diagnostic system has detected: Throttle/Pedal Position Sensor A Circuit Low Input. This is a serious severity code.
- Keep driving?
- Limited driving only
- DIY difficulty
- medium
- Estimated cost
- $30-$120 for a standalone bolt-on throttle position sensor (DIY-friendly). On most modern drive-by-wire vehicles the TPS is built into the electronic throttle body and isn't sold separately, so the fix is a full throttle-body replacement: roughly $250-$650 parts and labor. Wiring or connector repair instead runs about $75-$250 in diagnostic labor.
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Common Symptoms
- Check Engine Light on
- Reduced throttle response
- Engine may idle high or low
- Possible limp mode
- Hesitation under acceleration
Probable Causes (Ranked by Likelihood)
- TPS signal voltage below minimum threshold Very High
- Short to ground in TPS signal wire High
- Broken or shorted TPS internals High
- Missing 5V reference voltage to TPS Moderate
Common Fixes by Vehicle
What techs usually find when diagnosing P0122 on specific vehicles — tap your vehicle for the fix and the exact part:
2009-2020 Ford F-150/Explorer 3.5L/5.0L easy DIY
The throttle position sensor is integrated into the electronic throttle body on modern Ford trucks. Check the wiring connector for backed-out pins or corrosion first. If the connector is good, the throttle body assembly needs replacement (Motorcraft). Do NOT clean the TPS contacts -- the carbon resistive element is easily damaged. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30 min2007-2017 Toyota Camry/Corolla 2.5L easy DIY
The TPS is part of the electronic throttle body assembly on the 2AR-FE. Check for 5V reference voltage at the sensor connector with the key on. If the reference voltage is missing, check the ECU wiring. If 5V is present and the signal is low, replace the throttle body (Denso). Perform a throttle relearn after replacement. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30-45 min2008-2019 Honda Accord/CR-V 2.4L easy DIY
Check the TPS connector for corroded or loose pins. Honda TPS circuits are sensitive to resistance in the ground circuit. Clean the connector pins with electrical contact cleaner. If the TPS voltage stays below 0.5V with the throttle open, the throttle body assembly (Honda) needs replacement. Perform an idle relearn after installation. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30 minFrequently Asked Questions
Will P0122 put my car in limp mode?
On many vehicles, yes. When the throttle position sensor reads below its minimum valid voltage, the ECU cannot determine throttle angle and may default to a fixed, limited throttle opening to allow the car to limp home.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Check TPS signal voltage at rest. Below 0.2V indicates a low signal fault.
-
Verify 5V reference supply at the TPS connector pin.
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Disconnect TPS. If voltage at signal wire goes to 5V, the TPS is shorting the signal low.
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Check wiring for shorts to ground.
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Replace TPS if reference is present but signal remains low.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
P0122 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- Ford Explorer and Ranger
- Chevrolet Blazer and S-10
- Jeep Cherokee and Wrangler
- Toyota Tacoma
- Nissan Xterra
Related Codes
See All Codes & Fixes for Your Vehicle
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