Chassis, generic

C0301 Air Suspension Compressor Relay

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

No reachable J2012 table, no GM keyword list such as PIP5094, no AA1Car chart and no NHTSA bulletin carries C0301. Makers that document this fault use their own numbers. Mercedes-Benz stores open-circuit compressor actuation on AIRMATIC cars as C1562 and, after moisture froze in the compressor and the start current blew the 40 A fuse, replaces compressor, fuse and relay together. Lexus reports C1752 on the 2013–17 LS460 when water corrodes the height control compressor, and Volvo tells dealers to swap fuse and compressor on 2017–18 models. The relay switches the compressor's heavy current on command of the suspension module. A worn compressor overloads its contacts; a relay that sticks closed keeps it running and can overheat it.

Likely causes

Relay contacts burnt or welded by excessive compressor current
Worn, seized or water-damaged compressor drawing too much current
Blown compressor fuse or corroded relay socket and wiring

Symptoms

  • Air suspension warning message, compressor silent
  • Vehicle sinks or leans after standing
  • Compressor runs continuously when the relay sticks

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–1,200
Time0.3–3 h

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

Parts involved

compressor relayair compressorair suspension module

Related codes

C0317C0312

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.