Home >> Land Rover >> 2022 >> Defender 90 S >> Repair and Diagnosis >> General Information >> Specifications Index >> Diagnostic Trouble Code Index DTC: CHASIS Control Module (CHCM) -- Defender/L663 >> Diagnostic Trouble Code Index - DTC: Chassis Control Module (CHCM) (G3139555) >> Description And Operation >> Chassis Control Module (CHCM) >> DTC C1A27-29: Compressor Circuit - Signal invalid >> Possible Causes