P0124: Throttle or pedal position sensor A signal dropping out intermittently
Throttle or pedal position sensor A signal dropping out intermittently
Severity: Severity not verified — if the car runs badly, have it inspected
The sources describe the fault and its symptoms but do not give a driving-safety rating, so the severity is not verified.
P0124 in short
P0124 means the engine computer saw the signal from throttle or accelerator pedal position sensor A drop out or glitch on and off. It often shows as hesitation, an unstable idle or a check engine light. Common causes are a worn sensor, a poor connector or damaged wiring, and rarely the computer.
The engine computer reads the throttle or pedal position sensor to know how much power you are asking for. P0124 is set when that signal is present but breaks up on and off rather than failing outright.
Because the fault comes and goes, a loose or corroded connector, a chafed wire or a worn sensor track is more likely than a total failure. The reference lists the sensor, an open or shorted circuit and the computer as the possible causes.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Throttle or pedal position sensor A worn or failing
Common general cause- Why it ranks here
- The sensor itself is the first item on the reference list and the part whose signal the code monitors.
- What would change this
- Rises if the scan tool shows the position reading jumping while the pedal or throttle moves smoothly. Falls if the reading stays smooth and wiring wiggle causes the dropout.
Cause 2: Open, shorted or corroded sensor wiring or connector
Common general cause- Why it ranks here
- An intermittent break in the circuit produces exactly this kind of on-off signal.
- What would change this
- Rises if wiggling the harness or connector makes the reading drop out. Falls if wiring tests good and the signal is stable.
Cause 3: Engine computer fault (rare)
Possible — needs testing- Why it ranks here
- Listed last by the reference; only considered after the sensor and circuit test good.
- What would change this
- Rises only after the sensor, power, ground and signal wire all test good. Falls if any earlier test finds a fault.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Look over the sensor connector for corrosion and the wiring for damage; check the throttle body for binding or dirt.
IfCorrosion, damage or binding found
It meansRepair or clean it and recheck.
Points to: Open, shorted or corroded sensor wiring or connector
IfEverything looks fine
It meansWatch the sensor signal live.
Step 2: Watch the throttle or pedal position reading on a scan tool while moving the pedal slowly, and wiggle the harness.
IfReading jumps or drops out
It meansThe sensor or its wiring is suspect.
Points to: Throttle or pedal position sensor A worn or failing
IfReading is smooth
It meansTest the circuit power, ground and signal.
Step 3: Check power, ground and signal wire continuity from the sensor connector to the computer.
Warning:Backprobing and disconnecting connectors can damage terminals or set other codes; follow the vehicle wiring diagram.
IfA circuit reading is out of range
It meansRepair the circuit.
Points to: Open, shorted or corroded sensor wiring or connector
IfAll circuits test good
It meansConsider the computer last.
Symptoms
- Hesitation or stumbling when you accelerate
- Unstable idle
- Check engine light on
- Rarely, no start
How to fix
Step 1: Inspect the sensor connector and wiring for corrosion or damage.
Step 2: Have the throttle body checked for dirt or binding and cleaned if needed.
Parts and cost context
- Electronic throttle body:Confirm the fault with testing before buying parts. Labour varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
We don't have reviewed vehicle-specific evidence for P0124 yet. The causes and tests above apply across vehicles.
Related codes
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error