P2602: Coolant Pump A Control Circuit Low
What to do
If the battery has been going flat when the car stands for a day or two, mention it — a fault of this kind can leave the coolant pump running after everything else has gone to sleep, and that is easily mistaken for a worn-out battery. Standing next to the front of the parked car and listening is a genuine test: these pumps can be heard.
Otherwise, watch the temperature gauge in slow-moving traffic and get it looked at rather than left. A seized pump can produce this code too, so the wiring and the pump both need testing before either is replaced.
What this code means
The coolant pump control circuit reads below its valid range — normally a short to ground, or a driver output that has failed closed.
Which way this presents depends on how the circuit is arranged, and both directions are worth knowing. Where the module switches the pump's earth, a short to ground runs the pump continuously — including when the vehicle is asleep. A pump that never stops is a parasitic drain large enough to flatten a battery over a weekend, and the usual conclusion is a tired battery rather than a pump that will not switch off. It is worth listening at the front of a parked car: these pumps are audible.
Where the arrangement is the other way round, the same short means the pump never runs, and the consequences are those at P2600 — including the loss of the run-on that protects a turbocharger after shutdown.
A seized pump motor also pulls the circuit down, so the reading may be reporting a mechanically failed pump rather than a wiring fault.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Faulty electric coolant pump · moderate
Less common
- Seized pump motor · moderate
- Corroded or loose connector · easy
Rare
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P2602.