P0123 The throttle position sensor A signal voltage is above its normal range

Throttle position sensor A circuit high

P0123 in short

P0123 means the throttle position sensor A voltage is higher than a working sensor should produce, usually from a failed sensor, an open ground, a short to voltage or electrical noise in the harness. Expect hesitation, rough idle or limp mode. Get it checked soon, and stop safely if power drops away or the engine stalls.

The throttle position sensor gets 5 volts and a ground from the engine computer and returns a signal that rises as the throttle opens. Saab's ME9 software sets P0123 when sensor 1 reads above 4.5 volts for more than a second.

A reading that high usually means the sensor's ground has opened, the signal wire is touching a voltage source, or the sensor has failed. TroubleCodes.net also notes high-input codes can follow excessive charging voltage.

Bulletins show other causes: Mazda traced P0123 to electrical noise in the engine harness on the Mazda6, and Chrysler replaced throttle bodies on some Jeeps that set it in cold weather.

Most likely causes

  1. Failed throttle position sensor or throttle body

    Common general cause
    Why it ranks here
    The sensor is the usual cause, and Chrysler replaced the throttle body for P0123 on some cold-climate Jeeps and Dodges.
    What would change this
    Likelier if the signal stays high with a good ground at the connector.
    How to test the electronic throttle body

  2. Open sensor ground or poor connector contact

    Common general cause
    Why it ranks here
    With the ground open, the signal floats toward the 5-volt reference; HELLA lists plug contact faults.
    What would change this
    Likelier if the ground drop is high or wiggling the connector changes the reading.

  3. Short to voltage or electrical noise in the harness

    Supported by vehicle data
    Why it ranks here
    Mazda fixed P0123 on some Mazda6s by adding a throttle body harness to cut electrical noise.
    What would change this
    Likelier on a Mazda covered by the bulletin or if the code sets with electrical loads switched on.

  4. Charging system overvoltage

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net says high-input codes can come from an alternator putting out too much voltage.
    What would change this
    Likelier if battery voltage with the engine running is well above normal.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes and freeze-frame data, and check throttle position voltage and battery voltage with the engine running

    Low riskTool: OBD-II scan tool

  2. Check the sensor connector for corrosion, then measure reference, ground and signal, and check the signal wire for a short to voltage

    Best left to a shopTool: Digital multimeter

    Warning:Back-probing sensor and computer circuits can damage terminals or the computer if done wrongly; follow the maker's procedure.

Symptoms

  • Check engine light, sometimes with an ETC or wrench light
  • Hesitation or stumbling on acceleration
  • Unstable or high idle
  • Limp mode or sudden loss of power Gets more serious: stop and have it checked.
  • Engine stalls Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

  1. Ask a dealer to check your VIN for bulletins; Chrysler, Mazda, Kia and Ford have published repairs that include P0123.

  2. Note whether it only happens in cold weather or with lights and fans on; both details point to known causes.

Parts and cost context

  • Electronic throttle body:Electronic throttle bodies usually come with the sensors and may need a relearn after fitting. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Jeep

  • 2007–2009 · Grand Cherokee

    Supported by vehicle data

    P0123 or P0222 in cold climates; Chrysler replaces the throttle body and clean air duct. Whether the bulletin is still current is not verified.

  • 2007–2009 · Liberty

    Supported by vehicle data

    Same cold-climate throttle body bulletin as the Grand Cherokee. Whether the bulletin is still current is not verified.

  • SB-18-013-09Status unverified

    P0123 or P0222 in cold climates

    2007–2009grand-cherokee, liberty · issued · NHTSA 10030707

    In cold climates the MIL or ETC light may come on with P0123 or P0222; the repair replaces the electronic throttle body and clean air duct. Also covers Dodge Nitro.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Mazda

  • 2011–2013 · Mazda6

    Supported by vehicle data

    Engine harness noise can set P0123; Mazda adds a throttle body harness. Whether the bulletin is still current is not verified.

  • SB-01-008-13Status unverified

    P0123/P0222 from engine harness electrical noise

    2011–2013mazda6 · issued · NHTSA 10053734

    Abnormal electrical noise in the engine harness can set P0123 and/or P0222; a throttle body harness is installed.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Kia

  • 2001–2007 · Optima

    Supported by vehicle data

    Kia bulletin for hesitation or the MIL with P0123. Whether the bulletin is still current is not verified.

  • 038Status unverified

    Hesitation or MIL with P0123

    2001–2007optima, sportage · issued · NHTSA 10023626

    Information on engine hesitation or the MIL for P0123.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0122The throttle position sensor A signal voltage is below its normal range

    Shares causes Common general cause

    P0122 is the opposite fault on the same sensor and wiring.

  • P0121The throttle position sensor A signal doesn't agree with what the engine computer expects, even though the voltage is within range

    Shares causes Common general cause

    P0121 is a plausibility fault on the same sensor.

All Electronic throttle and accelerator pedal codes

P0123 questions

Can I keep driving with this code?

Only gently and to a shop. The engine computer may limit power at any moment, so avoid motorways and heavy traffic until it is fixed. If the engine drops to idle, stalls or won't respond to the pedal, pull over safely and have it towed.

Sources and review

  1. P0123 Throttle Position Sensor A Circuit High Input — TroubleCodes.net
  2. Saab 9-3 (2008) ME9 DTC P0123 Throttle Position Sensor 1, Signal Too High — Saab Automobile (WIS)
  3. Electronic Throttle Control (Throttle-By-Wire) — AA1Car (Larry Carley)
  4. NHTSA recall 26V081: Electronic throttle body gears may break (2024-2025 Nissan Rogue 1.5L VC-Turbo) — Nissan North America / NHTSA ,
  5. Chrysler SB 18-013-09: P0123/P0222 in cold climates (Grand Cherokee, Liberty, Nitro) — Chrysler ,
  6. Throttle potentiometer (throttle position sensor) — HELLA Tech World
  7. Mazda SB-01-008-13: P0123/P0222 from electrical noise in the engine harness (Mazda6) — Mazda ,
  8. Saab 9-3 (2008) ME9 DTC P0122 Throttle Position Sensor 1, Signal Too Low — Saab Automobile (WIS)
  9. Saab 9-3 (2008) ME9 DTC P0121 Throttle Position Sensor 1, Out of Range — Saab Automobile (WIS)
  10. Kia bulletin 038: hesitation or MIL with P0123 (Optima, Sportage) — Kia ,
Last reviewed
Written by
Saurabh K.
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