Powertrain, generic · Hybrid propulsion

P0C23 Electric/Auxiliary Transmission Fluid Pump Control Module Circuit/Open

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P0C23 is set by the controlling module, usually the PCM, TCM or hybrid controller, when the circuit to the auxiliary pump control module is open. J2012 does not name the line further; in practice it is the command or enable wire. Ford's 2016 F-150 2.7L bulletin shows such a command: the PCM drives the pump with a duty cycle that a scan tool can vary from 20 to 90 percent. GM's ELR pump controller only runs its phase tests while a wake-up signal is on. No manufacturer publicly documents P0C23 itself. With the line open the pump gets no command and stays off, so auto-stop is disabled and pressure support is missing. P0C24 and P0C25 are the low and high variants, P0C2B to P0C2E the feedback line in the other direction.

Likely causes

Open command or enable wire between controller and pump module

Pushed-out or corroded terminal at the pump module or controller connector

Input stage of the pump control module faulty

Symptoms

Start-stop no longer works
MIL or transmission warning
Harsh engagement after an engine stop

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€50–1,500

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

aux trans pump control modulewiring harnesstcm

Related codes

P0C24 P0C25 P0B0D P0C2B P2796 U0287

References: law.cornell.edu, static.nhtsa.gov, gsi.ext.gm.com.