Powertrain, generic · Hybrid propulsion

P0C4F Drive Motor B Position Exceeded Learning Limit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0C4F covers the second traction motor: its resolver offset learn finished, but the angle it produced lies outside what the controller will accept. GM applies the same two tests as for motor A, an absolute correction above 30 degrees or a change of over 10 degrees against the value kept from earlier learns, both checked at key-off with the rotor nearly still and more than 192 V available. The 2011 Volt sets it on one trip as Type A; the 2016 and 2019 Volt tables also say Type A but wait for five key-off cycles with the angle out of range. No bulletin for this code has been published. A large offset jump usually means something mechanical changed, so the check after a motor or sensor job matters most. P0C18 means motor B was never learned.

Likely causes

Motor B resolver stator fitted in a different position after a repair
Learn disturbed by a moving rotor or unstable high voltage at key-off
Damaged motor B resolver giving a shifted angle

Symptoms

  • Malfunction indicator lamp after shutdown cycles
  • Reduced propulsion or motor B unavailable
  • Unusual noise or shudder under electric drive

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,000
Time0.5–8 h

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

Parts involved

drive motor b position sensorhybrid control module

Related codes

P0C4EP0C18P0A45P0A46

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.