Will P0122 put my car in limp mode?

Yes, on most vehicles. The ECM treats a TPS signal below minimum as a safety fault and limits engine power or speed to protect the drivetrain from unexpected commands.

Can the accelerator pedal sensor cause P0122 instead of the throttle body sensor?

Yes. Some vehicles use a separate accelerator pedal position sensor, which has its own codes (P0222, P0223). But P0122 specifically targets the throttle body TPS circuit.

How long can I drive with P0122?

Once the engine enters limp mode, highway driving is unsafe. Limp mode limits RPM and may restrict shift changes. Drive only to a nearby shop.

Codes › P0122

P0122: The throttle position sensor voltage is too low

Throttle/Pedal Position Sensor/Switch A Circuit Low Input

Moderate severityCan you keep driving?

Use caution. If the engine goes to idle and will not respond to the accelerator, pull over safely. A failed TPS can leave the engine unable to accelerate. Do not drive on highways until repaired.

What it means

P0122 means the TPS signal voltage is below the minimum the ECM accepts. The most common cause is a failed sensor, a broken wire, or a bad ground in the TPS circuit. On drive-by-wire systems, both TPS sensors inside the throttle body operate inversely: as one goes up, the other goes down. If one drops below its floor, the ECM flags P0122 and may enter limp-home mode, limiting engine speed.

Common causes

Failed TPS sensor (open or short to ground)An internally failed sensor pulls the output below the acceptable floor voltage.
Broken or grounded signal wireA wire that has chafed against metal grounds the TPS signal line to zero.
Corroded or damaged TPS connectorA connector with missing or bent pins breaks the signal path entirely.
Failed 5V reference supply to the TPSIf the reference voltage is lost, the sensor output is also near zero even if the sensor is good.

What it costs

TPS sensor replacement (cable)$80 to $250
Electronic throttle body replacement$300 to $800
Wiring repair$100 to $300

Symptoms

Check engine light on
Engine stuck at idle or limited RPM (limp mode)
No throttle response or severely delayed response
Stalling when trying to accelerate
Transmission stuck in one gear

What to do next

Check the TPS connector first, since a simple loose connector is the easiest fix. With a multimeter and the ignition on, verify 5V reference voltage at the sensor. If the reference is present but signal stays near zero, the sensor is internally shorted or the signal wire is grounded. Replace the sensor if wiring checks out clean. On drive-by-wire throttles, the sensor cannot be replaced separately from the throttle body on most vehicles.

Lewis shows the TPS sensor voltage in real time, including both sensor 1 and sensor 2 on drive-by-wire systems, so you can see which one is reading low. Download Lewis.

Related codes

FAQ

Will P0122 put my car in limp mode?: Yes, on most vehicles. The ECM treats a TPS signal below minimum as a safety fault and limits engine power or speed to protect the drivetrain from unexpected commands.
Can the accelerator pedal sensor cause P0122 instead of the throttle body sensor?: Yes. Some vehicles use a separate accelerator pedal position sensor, which has its own codes (P0222, P0223). But P0122 specifically targets the throttle body TPS circuit.
How long can I drive with P0122?: Once the engine enters limp mode, highway driving is unsafe. Limp mode limits RPM and may restrict shift changes. Drive only to a nearby shop.