Powertrain, generic (extended)

P2B5E Engine Coolant Flow Control Valve Position Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2B5E reports a position sensor reading below its valid window. On GM's 3.0-litre Duramax the valve sends its angle as a raw SENT value in percent of 5 V; anything under 2 % counts as too low, and 80 failures in 100 samples at 6.25 ms set a Type B fault, provided there is no SENT communication fault and the relay supplies more than 11 V. A broken 5 V reference, a sensor ground issue inside the valve or a damaged signal wire can produce such a value. GM includes P2B5E in the LM2 chafed-harness condition of bulletin 21-NA-149. The engine computer loses the actual position and stops closed-loop control of coolant flow. High reading: P2B5F; plausibility: P2B60.

Likely causes

5 V reference or signal wire interrupted or shorted to ground
Chafed engine harness on GM LM2 (21-NA-149)
Position sensor in the valve faulty

Symptoms

  • MIL on after two drives
  • Coolant flow no longer regulated, warm-up slower

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–1,500
Time0.5–8 h

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

Parts involved

engine coolant flow control valvewiring harnessecm

Related codes

P2B5DP2B5FP2B60

References: gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.