C0603 code meaning
Active Air Dam Control Circuit High
What C0603 means
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.
C0603 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0603
- Air dam system fault message
- Air dam does not deploy at highway speed
- Possible blown fuse for the air dam circuit
Common causes of C0603
- Most likelyControl wire shorted to a battery-fed wire in the front harness
- PossibleFault in the actuator electronics holding the line high
- Less likelyWrong pin assignment or splice after a previous bumper or harness repair
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Active air dam actuatorActive air dam module
What each part of C0603 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 03 | The exact fault in that area. |
What to do next
- Note C0603 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0603
What does C0603 mean?
C0603 means "Active Air Dam Control Circuit High". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with C0603?
C0603 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will C0603 fail an emissions test?
C0603 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0603 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C0603 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.