P0122 Code Meaning and Next Steps

First checks take 10 to 15 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The engine starts running much worse, stalls, or the warning light flashes.
!The vehicle begins to overheat or lose power sharply while the code is active.

If the light is steady and the vehicle still drives normally: Often yes for a short time, but it should not be ignored.

What to check first

Step-by-step checks

1
Free - no tools
Inspect the TPS connector and harness for looseness, corrosion, or damage
2
Free - no tools
Check whether the throttle plate moves smoothly and whether the live TPS signal changes with pedal movement
3
Basic tool needed
If the engine also has idle or throttle-system codes, treat them together
4
Basic tool needed
If the problem appeared after recent intake work, make sure the connector is fully seated and the throttle body was not disturbed
5
Basic tool needed
Use scan data to compare closed-throttle and part-throttle readings before replacing the part

If the code returns

-If the signal remains low after a harness inspection, the sensor becomes a stronger suspect.
-If the reading changes with a wiggle test, wiring is more likely than the throttle body itself.
-If the code returns after replacing the TPS, revisit the reference and ground circuit before buying another part.

Background

What this code means

P0122 is a generic OBD-II throttle position sensor code.

A low TPS signal often points to a sensor, wiring, or connector issue that makes the ECU think the throttle is barely open.

Weak throttle response, hesitation, or unstable idle can appear when the sensor reads too low.

Diagnosis

Common causes

Most common

TPS sensor low output

The sensor may not be reporting the expected closed-throttle voltage.

Common

Connector or wiring fault

A loose or damaged connection can pull the reading low.

Common

Throttle plate not closing correctly

Mechanical issues can make the signal look lower than expected.

Possible

Reference voltage issue

The sensor may be fine but the supply side is not.

Avoid these mistakes

What not to do

xDo not replace the sensor first if there is an obvious wiring, connector, or intake issue.
xDo not ignore drivability changes just because the code sounds like a sensor problem.

Parts

Parts that may need replacing

PartTypical costNotes

Throttle position sensor$30-$120Relevant when the signal is clearly low and the throttle body is mechanically sound.

Connector repair$15-$90Worth checking if the plug or pins are loose or corroded.

Throttle body cleaning$20-$80Useful if the plate is sticky or does not return cleanly.

Related OBD codes

P0120

P0120 usually means the throttle position sensor circuit is not behaving correctly.

P0123

P0123 usually means the throttle-position signal is reading too high.

P0101

P0101 usually means the mass airflow signal is outside the expected range or performance window.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0122 was expanded around common low throttle-position signal faults, including sensor wear, connector issues, and mechanical sticking.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0122 - P0122 Usually Means the Throttle Position Sensor Is Reading Too Low