Chassis, generic

C0603 Active Air Dam Control Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

With C0603 the air dam control circuit reads above its permitted level, which points to a lead shorted to battery voltage or to another powered wire in the front-end harness. Motor driver ICs like the DRV8873-Q1 list a short to battery as a separate protected fault and disable the affected output. GM's patent on air dam self-diagnosis compares commanded position with measured position and motor current, which lets the controller tell a wiring problem from a blocked or broken panel. No maker documents C0603 publicly. Ram's X96 warranty extension for 2019 Ram 1500 trucks shows that air dam faults can light the MIL there, but that case is the lost-communication code U0645. Expect a stationary panel and a system message.

Likely causes

Control wire shorted to a battery-fed wire in the front harness
Fault in the actuator electronics holding the line high
Wrong pin assignment or splice after a previous bumper or harness repair

Symptoms

  • Air dam system fault message
  • Air dam does not deploy at highway speed
  • Possible blown fuse for the air dam circuit

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–600
Time0.5–2.5 h

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

Parts involved

active air dam actuatoractive air dam module

Related codes

C0601C0602C0604C062F

References: ti.com, patents.google.com, static.nhtsa.gov.