OBD-II code · Powertrain (generic, extended)
P26D4 Engine Coolant Pump Supply Voltage Circuit Low
The dedicated supply voltage to the coolant pump module is below operating range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P26D4?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHigh-resistance battery feed
- PossibleWeak battery sags under pump current
- Less likelyConnector pins corroded - high contact resistance
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Smart Coolant Pump Module, Supply Circuit, Battery
Related codes
- P26D1Engine Coolant Pump Control Module System Voltage High
- P26D2Engine Coolant Pump Control Module Over Temperature
- P26D3Engine Coolant Pump Supply Voltage Circuit
- P26D5Engine Coolant Pump Supply Voltage Circuit High
- P26D6Engine Coolant Pump Clutch Control Circuit / Open
- P26D7Engine Coolant Pump Clutch Performance/Stuck Off
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.