P0CEC: Hybrid/EV Electronics Coolant Pump A Control Circuit High

P0CEC flags a pump control line that is held too high, normally a short to battery voltage on the output. GM's HPC2 tables of 2016 and 2019 (16OBDG02, 19OBDG02) look for it while the pump enable is on and the commanded duty cycle is between 0 and 10 %: a line reading high when it should be nearly off counts as a failure, and 16 of 20 samples at 250 ms set the code, Type B, two trips, with system voltage above 10.2 V. A pump with a line pinned high may run constantly or ignore speed requests, depending on its electronics. Open circuits belong to P0CE9, a line pulled low to P0CEB, the separate enable wire to P0CED. The fix is usually in the harness: a pinched wire touching a feed or moisture in a connector.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

Malfunction indicator lamp on
Pump runs permanently or does not respond to speed changes
Possible power limitation of the hybrid system

Most likely causes

Control wire shorted to a 12 V feed in the harness
Moisture or corrosion in the pump connector linking supply and control pins
Pump electronics feeding voltage back onto the control line
Output stage in the control module stuck high

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P0CEC means

P: Powertrain: engine and transmission
0: Generic code: same on every make
C: Subsystem depends on the code range
EC: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0CEC?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0CEC?

The most common causes are: control wire shorted to a 12 V feed in the harness; moisture or corrosion in the pump connector linking supply and control pins; pump electronics feeding voltage back onto the control line.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.