P27A0Four Wheel Drive (4WD) Range Signal Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P27A0 is logged when the line reporting which transfer case range is engaged (4WD high, 4WD low, neutral) reads above its highest valid level. Range encoders usually present a defined voltage or resistance band for each position; a value above all bands typically means the wire is open and pulled up inside the module, the encoder lost its ground, or the line touches a battery feed. No manufacturer documents P27A0 publicly. GM's 2008 Two-Mode Hybrid tables carry the same range information under P279D, and CARB 13 CCR 1968.2 asks for out-of-range checks on such inputs. P279F is the low-side partner, P279E the plausibility fault. With the range unknown, the module may refuse range changes or fall back to a default torque strategy.
- What you may notice
- 4WD indicator flashing or showing no range
- Shift between 4WD high and low refused
- Warning lamp or driveline message
- Likely causes
- LikelyRange signal wire or encoder ground interrupted (corroded or loose connector near the transfer case)
- PossibleSignal wire chafed against a powered conductor
- PossibleTransfer case range encoder or switch defective
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.