OBD Guide

P129D

Fuel Pump Driver Control Module Ignition On/Start Switch Circuit Low Voltage

P129D is an OBD-II diagnostic trouble code meaning: Fuel Pump Driver Control Module Ignition On/Start Switch Circuit Low Voltage. Common causes: problems with wiring or contacts in the fpdm control circuit, fuel pump control module (fpdm) malfunction. Estimated repair cost: $17–89.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$17–89 (est.)

Symptoms

  • Engine won't start
  • Floating idle speed
  • Loss of power during acceleration
  • The engine stalls
  • Check Engine light comes on

Causes

  • Problems with wiring or contacts in the FPDM control circuit
  • Fuel pump control module (FPDM) malfunction
  • Problems with the fuel pump relay
  • Low battery voltage
  • Engine control unit (ECU) malfunction

How to Fix

  1. Check battery voltage
  2. Inspect the wiring and contacts in the FPDM control circuit
  3. Check fuel pump relay
  4. Test the fuel pump control module (FPDM)
  5. If necessary, replace faulty components

Related codes

FAQ

What does the P129D code mean?

P129D is an OBD-II diagnostic trouble code that indicates: Fuel Pump Driver Control Module Ignition On/Start Switch Circuit Low Voltage

What causes a P129D error code?

The most common causes of P129D include: Problems with wiring or contacts in the FPDM control circuit; Fuel pump control module (FPDM) malfunction; Problems with the fuel pump relay; Low battery voltage.

How do I fix a P129D diagnostic trouble code?

To fix P129D: Check battery voltage. Inspect the wiring and contacts in the FPDM control circuit. Check fuel pump relay. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P129D?

Do not drive — repair immediately

How much does it cost to fix P129D?

The estimated repair cost for P129D is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat