OBD-II Code · Sensors
P0123
TPS Circuit High Input
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$80–$300
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
TPS voltage too high.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Limp mode
- Reduced power
Likely causes
- Failed TPSMost common
- Wiring short to power
Read the full diagnostic procedureP0123 means the TPS signal voltage is above the ceiling, typically over 4.8V on a 3-wire potentiometer or over the TPS1 maximum on a 6-wire ETC.
P0123 means the TPS signal voltage is above the ceiling, typically over 4.8V on a 3-wire potentiometer or over the TPS1 maximum on a 6-wire ETC. The ECM reads that as a WOT signal that physically cannot occur at the actual pedal position, which means the sensor has failed shorted to its 5V reference, the signal wire has shorted to a power rail in the harness, or the sensor ground has been lost (which pulls the signal up to the reference). On most platforms this drops the engine into severe reduced-power limp mode immediately because the ECM cannot tell a real WOT command from a faulted signal.
Cheapest-first ladder
- with key-on engine-off, scan-tool TPS voltage should sit at the closed-throttle calibrated rest (0.5-0.8V on most potentiometer TPS).
- If TPS reads 4.9V at idle with the pedal untouched, that is the P0123 signature.
- Unplug the connector and verify the signal wire drops to 0V with the sensor disconnected (open-circuit pulled to ground by the ECM); if it stays at 5V with the sensor unplugged, the harness is shorted to a 5V or 12V power source between the connector and the ECM. Verify the sensor ground is intact with under 0.1V drop, because a lost sensor ground will float the signal to reference voltage and look identical to a shorted sensor.
- Don't replace the ETC throttle body before checking the ground at the connector, because a corroded ground pin is the most common P0123 cause on Ford and GM trucks and cleaning the pin saves a $400 part.
Vehicle-specific patterns2004-2010 Ford F-150 5.4L 3V sees P0123 from a corroded ground pin in the ETC throttle body connector after water intrusion through the cowl drain, c…
- 2004-2010Ford F-150 5.4L 3V sees P0123 from a corroded ground pin in the ETC throttle body connector after water intrusion through the cowl drain, cleaning the connector and applying dielectric grease often clears it without replacement.
- 2007-2013GM Silverado/Tahoe 5.3L sees P0123 from internal ETC failure where TPS1 shorts to 5V reference internally; the throttle body must be replaced and idle relearned.
- 2008-2014Chrysler 300/Charger 5.7L Hemi sees P0123 from TIPM-related power distribution faults that feed back-EMF onto the TPS 5V reference, a TSB pattern.
- 2009-2016Subaru Legacy/Outback 2.5L sees P0123 from the TPS1 element failing open in a way that pulls the signal to the 5V reference rail.
Estimated repair$80 to $550.
Look up another code
P0123 — frequently asked
What does a P0123 code mean?
TPS voltage too high.
What causes a P0123 code?
Common causes: Failed TPS; Wiring short to power.
What are the symptoms of a P0123 code?
Typical symptoms: Check engine light; Limp mode; Reduced power.
Is it safe to drive with a P0123 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $80-$300.
How do I diagnose a P0123 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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