Powertrain, generic (extended)

P2DE7 Cold Start Engine Coolant Bypass Valve C Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

California requires a fault found while the cold-start warm-up strategy runs to be stored apart from the same fault found later. P2DE7 is that cold-start counterpart of P26BB for coolant valve C. GM's 2025 ECM tables (25OBDG03B) set it when the valve's measured angle is more than 12° off its target after the target has settled, or when the valve moves slower than calibrated, during 4 of 5 seconds. Extra conditions are a low-flow coolant mode (also during auto-stop), active catalyst warm-up, closed-loop position control without soft opening, soft closing or anti-stick routine, and outlet coolant above −20 °C. Type B, MIL after two trips. A slow valve can let coolant circulate too early, so engine and catalyst heat up later. Position-sensor faults (P23C3 ff.) block the test.

Likely causes

Rotary valve sluggish from deposits or worn seals
Valve actuator motor or gearing weak
Position sensor reading drifting without a circuit fault
Engine control software needing an update

Symptoms

  • Check engine light on (after two trips)
  • Engine and cabin heater warm up more slowly
  • Usually no change in driveability

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

coolant bypass valve c

Related codes

P26BBP23C3P2DE8P2E81P2DE9

References: gsi.ext.gm.com, law.cornell.edu.