Faulty throttle position sensor or switch (both sources). Wiring or connector problems, such as corrosion, breaks, chafed wires or a short to ground (both sources). Sensor not mounted securely, or not aligned or rotated correctly when installed (OBD-Codes.com). Torn or jammed floor mats interfering with the accelerator pedal (RepairPal only). A damaged engine computer (PCM), which OBD-Codes.com lists as a possible but less common cause.

Repair damaged, chafed or corroded wiring or connectors. Replace the throttle position sensor or accelerator pedal sensor if testing confirms it's faulty. Re-mount or adjust the sensor so it is properly aligned. Fix or replace floor mats that interfere with the pedal. Repair or replace the engine computer only after the sensor and wiring test good.

P0122🔧 Throttle position / accelerator pedal sensorStop and fix promptly

P0122: Throttle Position Sensor A Circuit Low (Meaning, Causes, Fixes)

Q: What does P0122 mean?

P0122 means the engine computer is seeing too low a voltage from throttle (or accelerator pedal) position sensor A. Common causes are a faulty sensor, damaged or shorted wiring, a poor connection, or a sensor that isn't mounted or aligned correctly. The throttle position sensor sits on the throttle body and tells the engine computer how far the throttle is open; on cars with electronic throttle, a pedal position sensor in the accelerator pedal does a similar job. As you press the pedal, the sensor's voltage signal normally rises. P0122 sets when the computer sees the signal from sensor circuit A stay below its lower limit. OBD-Codes.com says that limit is about 0.17 to 0.20 volts on some vehicles, and that a low reading can come from an open circuit, a short to ground in the signal wire, or a lost 5-volt reference supply. It is a generic OBD-II code, so it applies to most 1996 and newer vehicles, though the exact repair steps vary by make and model. RepairPal names the code Throttle/Pedal Position Sensor/Switch A Circuit Low, while OBD-Codes.com uses Throttle Position Sensor/Switch A Circuit Low Input; they describe the same fault.

Q: Can I keep driving with P0122?

Stop and fix promptly. Get it checked soon, and be careful driving. RepairPal rates P0122 Urgent and says the engine computer may limit the car to about 20 mph or less (limp home mode) because it can't tell how much power you're asking for. OBD-Codes.com lists stalling, surging and little or no acceleration as possible symptoms, which can be dangerous in traffic. If the car stalls, surges or won't accelerate, don't drive it in traffic or on the highway until it's fixed.

Reviewed 2026-10-22 · Based on 2 cited source(s)

What P0122 means

The throttle position sensor sits on the throttle body and tells the engine computer how far the throttle is open; on cars with electronic throttle, a pedal position sensor in the accelerator pedal does a similar job. As you press the pedal, the sensor's voltage signal normally rises. P0122 sets when the computer sees the signal from sensor circuit A stay below its lower limit. OBD-Codes.com says that limit is about 0.17 to 0.20 volts on some vehicles, and that a low reading can come from an open circuit, a short to ground in the signal wire, or a lost 5-volt reference supply. It is a generic OBD-II code, so it applies to most 1996 and newer vehicles, though the exact repair steps vary by make and model. RepairPal names the code Throttle/Pedal Position Sensor/Switch A Circuit Low, while OBD-Codes.com uses Throttle Position Sensor/Switch A Circuit Low Input; they describe the same fault.

Severity: can I keep driving?

Stop and fix promptly

Get it checked soon, and be careful driving. RepairPal rates P0122 Urgent and says the engine computer may limit the car to about 20 mph or less (limp home mode) because it can't tell how much power you're asking for. OBD-Codes.com lists stalling, surging and little or no acceleration as possible symptoms, which can be dangerous in traffic. If the car stalls, surges or won't accelerate, don't drive it in traffic or on the highway until it's fixed.

Common symptoms

Check engine light on (RepairPal)
In many cases no other symptoms (RepairPal; OBD-Codes.com notes the problem may be intermittent if there are no symptoms)
Hard starting (RepairPal)
Hesitation on acceleration (RepairPal), or little or no acceleration (OBD-Codes.com)
Rough or low idle, or a very high idle (OBD-Codes.com)
Stalling or surging (OBD-Codes.com)
Reduced power or limp home mode, with speed limited to about 20 mph or less (RepairPal)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Faulty throttle position sensor or switch (both sources)
Wiring or connector problems, such as corrosion, breaks, chafed wires or a short to ground (both sources)
Sensor not mounted securely, or not aligned or rotated correctly when installed (OBD-Codes.com)
Torn or jammed floor mats interfering with the accelerator pedal (RepairPal only)
A damaged engine computer (PCM), which OBD-Codes.com lists as a possible but less common cause

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Look over the throttle position sensor, its connector and wiring for breaks, corrosion or wires rubbing on something. OBD-Codes.com says rubbing or grounding wires are a common cause of intermittent P0122.
Check that the floor mat isn't torn, bunched up or jamming the accelerator pedal, as RepairPal suggests.
If the sensor was recently replaced, make sure it was installed correctly. OBD-Codes.com notes some sensors must be aligned, adjusted or rotated into place so the tab engages the throttle shaft.
If you have a multimeter and a service manual, check the sensor's 5-volt reference, ground and signal voltage against the manual's specs.

Typical fixes

Repair damaged, chafed or corroded wiring or connectors
Replace the throttle position sensor or accelerator pedal sensor if testing confirms it's faulty
Re-mount or adjust the sensor so it is properly aligned
Fix or replace floor mats that interfere with the pedal
Repair or replace the engine computer only after the sensor and wiring test good

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The car goes into limp mode, stalls or surges
The wiring and connector look fine and you can't test the circuit voltages yourself
The code returns after a new sensor; RepairPal says a common misdiagnosis is replacing the sensor when the real problem is a poor connection or chafed wiring
The vehicle has electronic throttle control that may need a relearn procedure after repairs

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0122 serious?

It can be. RepairPal rates it Urgent and says the car may limit speed to about 20 mph to protect the engine and driver. OBD-Codes.com lists stalling and surging as possible symptoms. Some cars show only the check engine light, but it's worth fixing soon.

Can I drive with P0122?

If the car drives normally, a short trip to a shop is usually reasonable. If it stalls, surges, won't accelerate or is in limp mode, avoid traffic and highways until it's repaired.

Will a new throttle position sensor fix P0122?

Not always. RepairPal says sensors are often replaced when the real problem is a poor connection, chafed wiring or a damaged floor mat. Check the wiring and test the circuit before buying parts.

How much does it cost to fix P0122?

Neither source gives a repair cost. It depends on whether the fix is a wiring repair, a sensor or pedal assembly, or something else, so get a diagnosis and written estimate first.

Sources

Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.