System: Powertrain (P-Code)
SAE Standard (Generic)
Family: Engine Coolant Pump Clutch
Code P26D8: Engine Coolant Pump Clutch Stuck On
Diagnostic & Technical Explanation
Code P26D8 (Engine Coolant Pump Clutch Stuck On) sets when the ECM detects an open circuit, out-of-range voltage, or a stuck-on/stuck-off condition while controlling the electro-viscous or electromagnetic clutch on a belt-driven coolant pump, which decouples the pump at cold start to speed engine warm-up. Causes are a worn clutch coil, silicone fluid leakage from an electro-viscous unit, or damaged control wiring along the front accessory drive.
First-listed procedure
Rank #1
Repair pump clutch control wiring
Moderate DIY
This is the first procedure in the authored
consideration order, not a measured cause likelihood. Execute it only when its prerequisites
and diagnostic findings support it. Its cost and labor estimates (where known), the step-by-step procedure and the
remaining 2 procedure(s) are in the licensed dataset. Ordering context.
Full family: Engine Coolant Pump Clutch
What this page does not show
This page publishes the fault mechanism and the code index. The licensed dataset adds, for
every one of the 15,886 codes, the full authored repair set (56,729 procedures in total)
with the fields deliberately withheld here:
- Procedures 2..n after the first-listed procedure
- Aftermarket parts cost ranges in USD (
est_parts_cost_min/max_usd)
- Professional labor-hour estimates (
est_labor_hours)
- Step-by-step diagnostic and repair instructions
- Replacement-part mappings and catalog lookups
- 6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)