Powertrain, generic (extended)

P27BF Pressure Control Solenoid N Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P27BF indicates the control line of solenoid N is pulled too low, in practice a short to ground. GM's 23OBDG07 table for the Corvette dual-clutch gearbox checks synchronizer actuation valve 2 while its low-side switch is on: should the sense-pin voltage fall below about 1.7 V (tolerance 0.5 V), the driver chip reports a ground short; 150 ms confirmation, battery between 8.75 and 18 V, engine not cranking, Type A. With the line grounded the solenoid can be energized permanently and the controller loses control of it. Ford's TR9070 table calls the same event shorted switch on SPV2. A pinched harness against the case or water in a connector are frequent reasons.

Likely causes

Control wire chafed through to ground
Moisture or corrosion bridging the connector
Solenoid winding shorted to its housing

Symptoms

  • MIL on immediately
  • Unintended gear actuation or locked-out gears
  • Limp mode

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time1–4 h

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

Parts involved

pressure control solenoid nwiring harness

Related codes

P27C0P27BDP27BEP27BBP08CAP27C7

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