01 Demystifying OBD-II Trouble Codes: An In-Depth Look at Auto… • 02 How to Change a Car Tire • 03 How Expansion Chambers Boost the Power of 2-Stroke Engines • 04 P0023 B camshaft position - actuator circuit (Bank 2) • 05 How to Become a Pilot: A Guide for Aspiring Aviators • 06 B1700 – Body Network Communication Fault: Module Data Loss • 07 Front Wheel Vibration at High Speed: Troubleshooting and Fi… • 08 How do driverless cars navigate without road markings? • 09 Understanding Gear Ratios: How Transmissions Impact Perform… • 10 How Adaptive Cruise Control Actually Works •

DTC codes / P26xx · Computer and output circuits / P2600

P2600Coolant Pump Control Circuit/Open

P2600 indicates that the engine control module (ECM) has detected an open circuit or no continuity in the electrical path for the coolant pump control circuit. The ECM commands the pump on or off and monitors the circuit for expected voltage or current; when the signal is missing or out of range, it sets this generic code.

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 warning light or temperature gauge climbing above normal
  • Coolant pump may not run, leading to poor heater performance
  • Possible fan running constantly or at high speed as a failsafe
  • In rare cases, the engine may stall or fail to start due to safety logic

Common causes, most likely first

  1. Open or damaged wiring in the coolant pump control circuit (broken wire, corroded connector)
  2. Failed coolant pump (electric pump motor open internally)
  3. Blown fuse or faulty relay supplying power to the coolant pump
  4. Poor ground connection at the pump or chassis
  5. Faulty coolant pump control module (if equipped separately)
  6. ECM internal driver failure or software issue (less common)
  7. Aftermarket accessories tapped into the circuit causing interference

How to diagnose and fix it

  1. Perform a visual inspection of the coolant pump, its connector, and the wiring harness for damage, corrosion, or loose pins
  2. Check all fuses and relays related to the coolant pump circuit and replace any that are blown or faulty
  3. Disconnect the pump connector and use a multimeter to check for battery voltage at the power terminal with the key on
  4. Measure resistance across the pump motor terminals; an open circuit (infinite resistance) indicates a failed pump
  5. Check continuity of the control wire from the ECM to the pump connector to rule out an open circuit
  6. Verify ground integrity by measuring voltage drop from the pump ground terminal to battery negative
  7. If all electrical checks pass, suspect the ECM; consult factory service information for further diagnostics before replacement

Don't overlook the simple electrical checks

  • A loose or corroded ground connection at the pump can mimic a failed pump and is often missed during diagnosis.
  • Some vehicles use the coolant pump for both engine cooling and heater operation, so a lack of heat can be the first clue.
  • The code can be set by a momentary open circuit, so intermittent faults may require wiggle-testing the harness while monitoring live data.
  • Aftermarket alarm or remote start installations frequently tap into the coolant pump circuit and cause opens.
  • On vehicles with a separate control module, the module itself can fail and set P2600 even when the pump is good.

Can I keep driving with P2600?

It is not safe to continue driving with this code because the coolant pump may not operate, leading to rapid engine overheating and potential severe damage. Have the vehicle towed or drive only a very short distance to a repair shop while closely monitoring the temperature gauge.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage