P2602 Code: Coolant Pump Control Circuit Low

What the P2602 code means

Many modern engines use electric coolant pumps, or mechanical pumps with a controlled clutch. The computer decides when to circulate coolant so the engine warms up sooner and so the turbo is cooled after you shut the engine off.

The computer watches the control circuit from its own driver transistor. The P2602 code reports low voltage in the control circuit (a short to ground or a missing supply). Before you replace the component, check the fuse, relay, connector and wiring, which are the most common cause.

Some pumps talk to the computer with a PWM signal or over the LIN bus.

To confirm it, unplug the component with the key on and watch what happens to the reading or the code. If the value jumps to the opposite extreme, the wiring is fine and the component itself is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P2602 code symptoms

• Check engine light or another warning light on.
• Overheating of the engine or the turbo.

Likely causes of the P2602 code

1. Control wire shorted to ground. The component may stay on all the time, or the computer cuts the command to protect itself.
2. Interrupted supply: a blown fuse, a bad relay or a cut wire.
3. Component shorted, with resistance far lower than specified.
4. Connector with moisture, which creates a path to ground.

How to diagnose the P2602 code step by step

1. Command the component with the scan tool and check whether it responds.
2. Check the fuse and relay. Measure voltage on both sides of the fuse and swap the relay with an identical one.
3. Measure the supply at the connector: battery voltage with the key on or when it is commanded.
4. Measure the component resistance and compare it with the manual, and check the insulation to ground too.
5. Check the control wire: continuity to the computer and no short circuits.

How to fix the P2602 code

• Repair the connector, the wiring or the supply.
• Replace the coolant pump if it does not respond with correct supply and command.
• Clear the codes and verify.

Technical reference data

• 12 V supply and PWM or LIN control.
• Approximate values only: check the manufacturer data for your vehicle.

Brand-specific notes

The unplug test splits the pump from the wiring quickly on a low reading. Do it before you buy a pump for the P2602 code.

P2602 on BMW

Common on BMW, where the main coolant pump is electric.

P2602 on Volkswagen and Audi

Common on these makes, where an auxiliary pump is used.

P2602 on Ford EcoBoost and Mercedes-Benz

Also common on Ford EcoBoost engines and on Mercedes-Benz.

Frequently asked questions about P2602