P0122 The throttle position sensor A signal voltage is below its normal range

Throttle position sensor A circuit low

P0122 in short

P0122 means the throttle position sensor A voltage is lower than it should ever be, usually from a failed sensor, a wire shorted to ground or an open in the 5-volt supply. The computer may limit throttle opening and power. Get it fixed soon, and stop safely if the engine loses power or stalls.

The throttle position sensor is a variable resistor or Hall sensor fed with 5 volts. Its signal rises as the throttle opens, so a reading near zero is something a working sensor shouldn't produce.

Saab's ME9 service information sets P0122 when sensor 1 reads below 0.20 volts for more than a second. That usually points to the signal wire shorted to ground, a lost 5-volt supply, a broken connection or a sensor that has failed internally.

KBB notes the fail-safe can restrict throttle opening to a few degrees, so the car feels slow and may idle high or stall. Some bulletins trace the code to wiring chafing on engine parts.

Most likely causes

  1. Failed throttle position sensor (part of the throttle body on electronic throttles)

    Common general cause
    Why it ranks here
    KBB and HELLA list the sensor first; Honda has a bulletin for P0122 on the CR-V.
    What would change this
    Likelier if the signal stays low with good supply and ground at the connector.
    How to test the electronic throttle body

  2. Signal wire shorted to ground or chafed harness

    Supported by vehicle data
    Why it ranks here
    A short to ground drags the signal low; GM traced P0122 on some crossovers to the engine harness rubbing on the cylinder head.
    What would change this
    Likelier if the harness shows rubbing or the reading changes when it's moved.

  3. Open circuit, lost 5-volt supply or poor connector contact

    Common general cause
    Why it ranks here
    A lost supply or open signal path also reads low; HELLA lists plug contact faults and moisture.
    What would change this
    Likelier if the 5-volt reference is missing at the connector.

  4. Accelerator pedal sensor or shared 5-volt circuit fault

    Possible — needs testing
    Why it ranks here
    KBB lists the pedal sensor; on many cars it shares a 5-volt reference with the throttle sensor, so a short in one can pull the other down.
    What would change this
    Likelier if pedal sensor codes are stored too.
    How to test the accelerator pedal position sensor

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 live throttle position voltage at closed throttle

    Low riskTool: OBD-II scan tool

  2. With the ignition off, inspect the throttle body connector and harness for rubbing, especially where it passes engine parts

    Use cautionTool: Flashlight

    Warning:Let the engine cool before reaching around the cylinder head and exhaust, and keep fingers out of the throttle bore.

  3. Measure the 5-volt reference, ground and signal at the sensor connector and check the signal wire for a short to ground

    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 a throttle or wrench warning
  • Slow acceleration or limp mode Gets more serious: stop and have it checked.
  • High or unsteady idle
  • 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; Honda, GM, Mazda and Ford have published repairs that include P0122.

  2. Note whether it happens after rain or over bumps. That points the shop toward a wiring or connector fault.

Parts and cost context

  • Electronic throttle body:On most electronic throttles the sensor isn't sold separately, so the throttle body is replaced and may need a relearn. Older cable throttles may have a separate sensor. 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

Honda

  • 2002–2004 · CR-V

    Supported by vehicle data

    Honda published a bulletin for the check engine light with P0122. Whether the bulletin is still current is not verified.

  • 04-008Status unverified

    MIL on with DTC P0122

    2002–2004cr-v · issued · NHTSA 10008369

    Check engine light with DTC P0122.

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

Chevrolet

  • 2010–2011 · Traverse

    Supported by vehicle data

    Engine harness rubbing on the bank 2 cylinder head can set P0122 among other codes. Whether the bulletin is still current is not verified.

  • PI-0220Status unverified

    MIL with misfire and sensor DTCs including P0122 from engine harness chafing

    2010–2011acadia · issued · NHTSA 10036490

    MIL with DTCs including P0122 and P0222, caused by the engine harness contacting the back of the bank 2 cylinder head. Also covers Buick Enclave and Chevrolet Traverse.

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

Mazda

  • 2009–2010 · Tribute

    Supported by vehicle data

    P0122 with P2135 and P2111 and intermittent reduced power. Whether the bulletin is still current is not verified.

  • SB-01-007-13Status unverified

    Wrench light or MIL with P2135, P2111, P0122

    2009–2010tribute · issued · NHTSA 10052158

    Wrench light or MIL with P2135, P2111 and P0122, possibly with rough idle, reduced power or wrong idle speed.

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

Ford

  • 2014–2016 · Transit Connect

    Supported by vehicle data

    Ford lists P0122 among many DTCs on the 2.5L Transit Connect. Whether the bulletin is still current is not verified.

  • TSB 16-0163Status unverified

    MIL and drivability issues with multiple DTCs, 2.5L

    2014–2016transit-connect · issued · NHTSA 10094582

    Constant or intermittent MIL with drivability issues and one or more of many DTCs including P0122, P0131 and P2127.

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

  • P0123The throttle position sensor A signal voltage is above its normal range

    Shares causes Common general cause

    P0123 is the opposite fault, a signal that is too high, 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.

  • P2135Two throttle or pedal position sensor signals (A and B) that should agree with each other don't

    Shares causes Supported by vehicle data

    Mazda lists P0122 with P2135 and P2111 on the Tribute.

  • P2111The engine computer commanded the electronic throttle to close further but saw it stay more open than expected

    Shares causes Supported by vehicle data

    Mazda lists P0122 with P2111 for rough idle and reduced power on the Tribute.

All Electronic throttle and accelerator pedal codes

P0122 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. P0122 Throttle/Pedal Position Sensor A Circuit Low Input — Kelley Blue Book
  2. Saab 9-3 (2008) ME9 DTC P0122 Throttle Position Sensor 1, Signal Too Low — Saab Automobile (WIS)
  3. Electronic Throttle Control (Throttle-By-Wire) — AA1Car (Larry Carley)
  4. NHTSA complaint ODI 10449313: 2009 Toyota Corolla Matrix, dealer found P0121 and an internal throttle body sensor fault after loss of acceleration — NHTSA Office of Defects Investigation
  5. NHTSA complaint ODI 10255038: 2005 Ford F-150, dealer found P0121/P2104/P2112 and a throttle body sticking closed after a stall — NHTSA Office of Defects Investigation
  6. Throttle potentiometer (throttle position sensor) — HELLA Tech World
  7. Honda 04-008: MIL on with DTC P0122 (CR-V) — American Honda ,
  8. GM PI-0220: MIL with P0122 and other DTCs from engine harness chafing (Acadia, Enclave, Traverse) — General Motors ,
  9. Saab 9-3 (2008) ME9 DTC P0123 Throttle Position Sensor 1, Signal Too High — Saab Automobile (WIS)
  10. Saab 9-3 (2008) ME9 DTC P0121 Throttle Position Sensor 1, Out of Range — Saab Automobile (WIS)
  11. Mazda SB-01-007-13: wrench light/MIL with P2135, P2111, P0122 (Tribute) — Mazda ,
  12. Ford TSB 16-0163: MIL and drivability issues with multiple DTCs (Transit Connect 2.5L) — Ford Motor Company ,
Last reviewed
Written by
Saurabh K.
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