P2122 — Throttle/Pedal Position Sensor/Switch "D" Circuit Low

OBD2 code P2122 flags a problem with the throttle and intake air metering (throttle/pedal position sensor/switch "D" circuit low). Short, gentle driving to a shop is usually possible. Common culprits: dirty throttle body or stuck throttle plate, contaminated or failed MAF/MAP sensor, faulty throttle position sensor or pedal sensor.

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution. Many throttle faults put the car into limp mode with limited power — enough to reach a shop, not for highway trips. If the engine stalls or the pedal stops responding, do not drive.

How to diagnose with an OBD scanner

  1. Read the code and freeze frame Connect an OBD2 scanner, confirm P2122 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the throttle and intake air metering for damage, corrosion, chafing or poor contact.
  4. Subsystem check Check for supply voltage at the throttle/pedal position sensor/switch "D" connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
  5. Subsystem check Inspect and clean the throttle body; check that the plate moves freely.
  6. Subsystem check Watch throttle position and MAF/MAP readings in live data while pressing the pedal — values should change smoothly.
  7. Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2122 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P2122 (parts and labor, USD, independent shop rates): Clean the throttle body: $80–$200; Replace the throttle body assembly: $250–$700; Replace the MAF or MAP sensor: $150–$400. Overall, fixing P2122 usually costs between $80 and $700. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How do I diagnose P2122 myself?

Start with a scan: confirm P2122, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the throttle/pedal position sensor/switch "D", and verify the suspect component against live data before buying parts.

How much does it cost to fix P2122?

Clean the throttle body — $80–$200; Replace the throttle body assembly — $250–$700; Replace the MAF or MAP sensor — $150–$400. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of P2122?

Drivers most often notice: poor throttle response, unstable or high idle, Check Engine Light on, limp-home mode with reduced power.

What does OBD2 code P2122 mean?

OBD2 code P2122 flags a problem with the throttle and intake air metering (throttle/pedal position sensor/switch "D" circuit low). Short, gentle driving to a shop is usually possible. Common culprits: dirty throttle body or stuck throttle plate, contaminated or failed MAF/MAP sensor, faulty throttle position sensor or pedal sensor.

What is the most common cause of P2122?

The most common causes are: dirty throttle body or stuck throttle plate, contaminated or failed MAF/MAP sensor, faulty throttle position sensor or pedal sensor.

What does P2122 mean?

P2122 (Throttle/Pedal Position Sensor/Switch "D" Circuit Low) is stored when self-diagnostics detect abnormal readings or behaviour of the throttle and intake air metering. It belongs to the powertrain (engine/transmission) category.

“Circuit low” means the voltage on the throttle/pedal position sensor/switch "D" circuit stays below the expected minimum — close to ground. The usual physical reasons are a short to ground, a chafed wire touching metal, a missing supply voltage, or a failed component dragging the signal down.

This code does not appear from a single bad reading: the module must see the fault condition repeat under defined operating conditions before it turns on the warning light. The freeze frame captured with P2122 — engine load, rpm, temperature, speed — tells you exactly when the problem occurs, so reproduce those conditions when testing.

Common symptoms of P2122

  • poor throttle response
  • unstable or high idle
  • Check Engine Light on
  • limp-home mode with reduced power
  • stalling when coming to a stop

What causes P2122?

  • missing supply voltage to the throttle/pedal position sensor/switch "D"
  • failed throttle/pedal position sensor/switch "D" pulling the signal low
  • signal wire shorted to ground (chafed insulation)
  • wiring or connector faults in the throttle circuit
  • failed electronic throttle motor
  • contaminated or failed MAF/MAP sensor
  • intake air leaks after the MAF sensor
  • faulty throttle position sensor or pedal sensor
  • dirty throttle body or stuck throttle plate

How to diagnose P2122

  1. Connect an OBD2 scanner, confirm P2122 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Visually inspect the wiring harness and connectors related to the throttle and intake air metering for damage, corrosion, chafing or poor contact.
  4. Check for supply voltage at the throttle/pedal position sensor/switch "D" connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
  5. Inspect and clean the throttle body; check that the plate moves freely.
  6. Watch throttle position and MAF/MAP readings in live data while pressing the pedal — values should change smoothly.
  7. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2122 does not return.

How to fix P2122

Start with the cheapest and most common causes before replacing expensive parts:

  • Clean the throttle body — $80–$200
  • Replace the throttle body assembly — $250–$700
  • Replace the MAF or MAP sensor — $150–$400

How much does it cost to fix P2122?

Repair cost depends on which component actually failed. Typical scenarios for P2122 (parts and labor, USD, independent shop rates):

  • Clean the throttle body: $80–$200
  • Replace the throttle body assembly: $250–$700
  • Replace the MAF or MAP sensor: $150–$400

Overall, fixing P2122 usually costs between $80 and $700. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Can you drive with P2122?

Drive with caution. Many throttle faults put the car into limp mode with limited power — enough to reach a shop, not for highway trips. If the engine stalls or the pedal stops responding, do not drive.

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