Faulty coolant pump (electrical failure or seized motor); Damaged or corroded wiring harness or connector at the pump; Short to ground in the control circuit wiring; Open circuit in the power or ground circuit to the pump; Failed coolant pump relay or fuse (if applicable); Faulty engine control module (ECM) driver circuit (rare)

DTC codes / P26xx · Computer and output circuits / P2602

P2602Coolant Pump Control Circuit Low

Q: What does code P2602 mean?

Coolant Pump Control Circuit Low. P2602 indicates the engine control module (ECM) has detected an abnormally low voltage on the control circuit for the engine coolant pump, which is often an electric auxiliary pump used for turbocharger cooling or cabin heat. The ECM commands the pump on and monitors the circuit, but the feedback voltage stays below the expected threshold, suggesting a short to ground, an open circuit, or a faulty pump.

P2602 indicates the engine control module (ECM) has detected an abnormally low voltage on the control circuit for the engine coolant pump, which is often an electric auxiliary pump used for turbocharger cooling or cabin heat. The ECM commands the pump on and monitors the circuit, but the feedback voltage stays below the expected threshold, suggesting a short to ground, an open circuit, or a faulty pump.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Engine may enter limp mode or reduced power mode on some vehicles
Overheating or elevated coolant temperatures, especially after the engine is shut off
The coolant pump may not run, leading to poor cabin heat or turbocharger cooling issues
A whining or grinding noise from the pump area if the pump is failing mechanically

Common causes, most likely first

Faulty coolant pump (electrical failure or seized motor)
Damaged or corroded wiring harness or connector at the pump
Short to ground in the control circuit wiring
Open circuit in the power or ground circuit to the pump
Failed coolant pump relay or fuse (if applicable)
Faulty engine control module (ECM) driver circuit (rare)

How to diagnose and fix it

Inspect the coolant pump connector and wiring for corrosion, damage, or loose pins
Check the coolant pump fuse and relay (if equipped) and replace if blown or faulty
Measure resistance of the coolant pump motor and compare to specification
Test the control circuit for a short to ground or open circuit using a multimeter
Command the coolant pump on with a scan tool and verify operation and current draw
Replace the coolant pump if it fails electrical or mechanical testing
Clear the diagnostic trouble codes and verify the repair with a test drive

Common Misdiagnosis Traps for P2602

A low voltage code on the control circuit does not always mean the pump is bad; a chafed wire shorting to ground can set the same code and replacing the pump will not fix it.
Some vehicles use the coolant pump for turbocharger cooling after shutdown, so a failure may not cause overheating while driving but can lead to turbo damage over time.
The ECM may set P2602 if the pump is disconnected during service; always check for recent repairs before condemning parts.
On certain models, the coolant pump is controlled by a separate module, and a communication fault with that module can mimic a circuit low code.
A weak battery or charging system issue can cause low voltage on the control circuit and set P2602 intermittently.

Can I keep driving with P2602?

It is generally safe to drive short distances to a repair shop, but avoid heavy loads, extended idling, or aggressive driving that increases engine heat. If the temperature gauge rises above normal or you notice coolant loss, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.