Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / P1122 — Pedal Position Sensor 1 Low Input

P1122 — Pedal Position Sensor 1 Low Input

Detailed page for trouble code P1122.

34,405codes
59brands
11,914generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

P1122

BMW P — Powertrain

Pedal Position Sensor 1 Low Input

Brand: BMW
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or disconnected accelerator pedal position sensor (PP sensor) connector
  • Broken, shorted, or corroded wiring between pedal sensor and ECU
  • Poor ground or low reference voltage (5V) to the sensor
  • Failed pedal position sensor (internal short or failed Hall/potentiometer)
  • Faulty ECU input channel (rare)
  • Aftermarket throttle controller, repairs, or incorrect replacement pedal not programmed

Symptoms

  • Reduced engine power or limp mode
  • Poor or no throttle response from accelerator pedal
  • Check Engine Light (MIL) stored
  • Unstable idle or sudden loss of power
  • Possible stored additional codes for throttle/pedal correlation

What to check

  • Read freeze frame data and all related DTCs with a capable scan tool (BMW-compatible preferred).
  • Visually inspect pedal connector, wiring harness, and nearby harness routing for damage, pin corrosion, or water ingress.
  • Check battery voltage and key-on engine-off (KOEO) reference voltage to the pedal sensor (should be ~5V).
  • Backprobe sensor connector: measure sensor output voltage at rest and while moving the pedal; note any drop to near 0V.
  • Check continuity and resistance between sensor ground and chassis ground; verify 5V reference continuity back to ECU.
  • Wiggle harness and connector with scan tool monitoring to detect intermittent faults.

Signal parameters

  • Reference supply: approx. 5 V (KOEO) at sensor reference pin
  • Sensor ground: near 0 V, chassis ground continuity
  • Sensor output (typical): ~0.4–1.0 V at rest rising smoothly to ~4.5 V at full pedal travel (specs vary by model/year)
  • Low input fault threshold: output near 0 V or significantly below expected idle voltage
  • Signal behavior: smooth, monotonic voltage change with pedal movement; no dropouts or sudden discontinuities

Diagnostic algorithm

  1. Connect a full-function scan tool. Record freeze frame, related DTCs (e.g., other pedal/throttle codes), and live pedal position data.
  2. Perform a visual inspection of the pedal assembly, connector, and harness for damage, corrosion, or water entry. Repair obvious issues.
  3. With ignition ON (engine OFF), verify sensor reference voltage (~5 V) at the pedal connector. If missing, trace wiring to ECU and check fuses/relays.
  4. Verify sensor ground continuity to chassis/ECU ground. Repair any high-resistance or open ground.
  5. Backprobe the sensor output (signal) pin. Observe voltage at rest and while slowly depressing the pedal—voltage should rise smoothly. If signal is near 0 V, verify wiring for short to ground.
  6. Wiggle the harness and connector while monitoring live data to identify intermittent opens/shorts.
  7. If wiring and connectors are sound but signal remains low, replace the pedal position sensor assembly. Use OEM part and follow BMW programming/calibration if required.
  8. If swapped sensor still fails and wiring is verified, test the ECU input channel for shorts or replace/repair ECU as a last resort (reference factory wiring diagrams and follow safety procedures).
  9. After repairs, clear codes, perform functional checks and a short test drive to confirm no reoccurrence.

Likely causes

  • Intermittent or damaged wiring/connector to pedal sensor (most common)
  • Failed pedal position sensor assembly
  • Corroded connector or poor ground
  • ECU fault or need for software/configuration after parts replacement (less common)

Fault status

⚠️ Status
P1122 - Pedal Position Sensor 1 Low Input (accelerator pedal sensor signal below expected range)
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0122 P0121 P0222 P0221 P2135 P2138
Repair manuals

Manual library for BMW

479

Browse 479 BMW manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

BMW

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .