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?
- Yes, but fix soon
- 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
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.
-
Disconnect TPS. If voltage at signal wire goes to 5V, the TPS is shorting the signal low.
-
Check wiring for shorts to ground.
-
Replace TPS if reference is present but signal remains low.
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 9W7Z-9E926-A). Ford TSB 11-5-3 covers throttle body circuit diagnostics. Do NOT clean the TPS contacts -- the carbon resistive element is easily damaged.
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 22030-28070). Perform a throttle relearn after replacement.
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 16400-R40-A02) needs replacement. Perform an idle relearn after installation.
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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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:
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