P26D1
Engine Coolant Pump Control Module System Voltage High
The smart coolant pump module reports the system voltage above operating range. Pump output is reduced or disabled to protect the module.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Alternator regulator failed to limit outputCommon
- Load dump transient after disconnecting a heavy loadLess likely
Parts involved
- Smart Coolant Pump Module
- Charging System
P26D1 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.