C0870 code meaning
Control Module Voltage Reference Output Circuit
What C0870 means
C0870 is missing from the accessible J2012 code lists; it is documented at GM, where it covers the 5 V reference that a module feeds to its sensors. Saab workshop pages for the 2011 9-5 and 9-4X use it in the suspension control module, which feeds five acceleration sensors on the body and at the wheels: subcode 03 means that line is shorted to ground and 07 that it touches battery voltage, each for 1.5 s, checked between 9 and 16 V. Electronic damping then shuts off for the ignition cycle. The fix is to unplug the sensors one by one and watch the reference return to 4.8-5.2 V. Under the older name Device Voltage Reference Output 1 Circuit, GM hybrid pickups of 2005 and 2007 used it for the pedal sensor supply of the steering pump (above 4.65 V or below 3.95 V, type C, no MIL).
C0870 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0870
- SERVICE SUSPENSION SYSTEM message
- Adaptive damping inactive for the rest of the trip
- Several acceleration sensor codes stored at once
Common causes of C0870
- Most likelyOne acceleration sensor shorting the shared 5 V reference
- PossibleReference line chafed to ground or to battery voltage
- Less likelyModule reference supply faulty, module replacement after wiring checks (Saab WIS)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Sensor reference voltage circuitSuspension control moduleVertical acceleration sensor
What each part of C0870 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 70 | The exact fault in that area. |
What to do next
- Note C0870 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 C0870
What does C0870 mean?
C0870 means "Control Module Voltage Reference Output Circuit". C0870 is missing from the accessible J2012 code lists; it is documented at GM, where it covers the 5 V reference that a module feeds to its sensors. It is a generic code, so it means the same on every make.
Is it safe to drive with C0870?
Drive gently and only to a workshop. With C0870 the car can go into limp mode (reduced power) to protect itself.
Will C0870 fail an emissions test?
C0870 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 C0870 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C0870 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.