Error code · Engine

P129F — Fuel pump power control module fuel pump speed signal incorrect

Don’t put off the repair

For makes: Chevrolet, Cadillac, GMC

A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.

Possible causes

What you can do yourself

  1. The engine may stall or not start. If it stalls while driving, switch on the hazard lights and get the car off the road.
  2. Check the fuel pump fuse and the fuel pump module connectors: corrosion, water, an unlatched connector.
  3. Check the engine ground: the ground strap is tight on the engine and on the body, with no corrosion. Per a GM bulletin, a loose ground sets many communication codes at once.
  4. Check the battery and terminals: at low voltage control units lose communication.

Stop and don’t drive on if:

  • The Check Engine light is flashing
  • The temperature gauge is in the red or the overheating light is on
  • The red oil pressure light is on
  • Smoke from under the bonnet, a burning or petrol smell
  • Strong jerking, knocking from the engine, or the car barely moves
OOleg’s tip: check the connector

Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.

Unplug and inspect connectors with the ignition off.

This is the GM meaning (Chevrolet, Cadillac, GMC). On other makes this number means something else: if your car isn’t made by GM, change the make at the top.

Source: GM 23-NA-102 (static.nhtsa.gov)

The explanation comes from the error code reference in the AvtoElektrik PRO app.

Need a mechanic’s help?

Couldn’t fix it yourself? Oleg, an auto electrician, does computer diagnostics and repairs: he comes out anywhere in Almaty or sees you at his workshop.

Want to figure it out yourself?

Oleg’s course “Car computer diagnostics with a scan tool”: how to hook up a scanner, read codes and live data, and use them to find the cause. The first lessons are free.

Scan tool diagnostics course →

Nearby codes

All codes in P10xx–P16xx →

Who keeps this reference

The reference is kept by Oleg Dmitriev, an auto electrician from Almaty with 26 years of experience: computer diagnostics of cars and trucks, repair of control units (ECUs). Can’t find the cause? Message him.