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DTC code page

P2122: Throttle/Pedal Position Sensor/Switch D Circuit Low Input

Quick answer: The ECU sees one of the pedal or throttle position circuits reading lower than expected, making accelerator input unreliable.

Drivers also search this fault as pedal position sensor low input, APP sensor D low, P2122 reduced power.

Severity: high Family: powertrain Related paths: 9
Meaning

What P2122 usually means

P2122 lives in the accelerator-pedal and position-correlation branch where reduced-power complaints often begin before the throttle body is ever proven bad. The control module is seeing a position signal on circuit D that is too low, which can happen with a short to ground, worn pedal sensor track, connector trouble, or reference-voltage loss. This is a high-value addition because APP low-input searches are common, they map tightly to P2138 and P2135, and they give the graph a stronger bridge between pedal-side faults and throttle-side strategy codes.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Look for companion P2127, P2138, or throttle-actuator codes because pedal faults often travel in groups.
  • Inspect the pedal connector area for moisture, kicked wiring, or aftermarket accessory damage.
  • Verify the reference voltage and ground before replacing the pedal assembly.
Driving risk

Can you keep driving?

P2122 affects the ECU’s trust in accelerator input, so reduced-power behavior can appear suddenly and should be taken seriously.

High urgency: If symptoms are active, reduce driving and diagnose quickly before secondary damage builds.
Likely causes

Common causes behind this code

  • Accelerator pedal position circuit is shorted low or partially grounded
  • Internal pedal sensor wear is pulling the D signal too low
  • Reference-voltage or ground issue is distorting pedal output
  • Connector or harness damage near the pedal assembly is affecting the signal
  • Moisture, corrosion, or physical strain at the pedal connector is creating low input

Cause phrases often tied to this code: short to ground, pedal sensor wear, reference voltage loss, connector problem, wiring fault.

Diagnostic order

Suggested workflow

  1. Capture freeze-frame and note whether the complaint happened during tip-in, cruise, or restart.
  2. Inspect pedal wiring and connector condition physically.
  3. Measure reference voltage, ground quality, and signal behavior through pedal travel.
  4. Compare the suspect signal to its paired pedal circuits and look for implausible spread.
  5. Replace the pedal assembly if the signal remains low with good wiring and supply.
Avoid guesswork

Common mistakes

  • Replacing the throttle body for a pedal-side signal fault.
  • Skipping reference-voltage checks and blaming the pedal immediately.
  • Ignoring physical connector damage low in the driver footwell.
Repair path

Practical fix guidance

  • Repair wiring, connector, or reference issues before replacing the pedal assembly.
  • Replace the pedal position sensor assembly when the low signal is internal and repeatable.
  • Confirm normal pedal response and no reduced-power return on a road test.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P2122

Useful when the driver knows the wording but not the exact DTC yet.

  • pedal position sensor low input
  • APP sensor D low
  • P2122 reduced power
Related search intent

Queries this page can answer naturally

  • P2122 code meaning
  • what does P2122 mean
  • throttle pedal position sensor switch D circuit low input
FAQ

Quick questions about P2122

Does P2122 mean the gas pedal is bad?

Sometimes, but wiring, reference-voltage, and connector issues can cause the same low-input pattern.

Why does P2122 trigger reduced power?

Because the ECU cannot trust accelerator input when one pedal signal is too low.

Can floor-area moisture cause P2122?

Yes. Pedal connectors live low in the cabin and can be affected by moisture or contamination.