U3015 code meaning
Control Module Ground C
What U3015 means
U3015 reports that the third ground path of a module, labelled C, is missing or no longer plausible. Three or four separate grounds are found mainly on units that drive heavy loads, such as brake, steering or power distribution modules, where control electronics and power stages return current through their own wires. No manufacturer documents U3015 publicly. The published logic for grounds A and B gives the pattern: GM's 19OBDG03B brake module compares the voltages on two grounds and flags one as lost once the ratio leaves ±0.9, and Ford's 26-2150 ties each ground letter to a specific body point. Which pin is C is defined only by that module's wiring diagram. A failing ground C can bring warning lamps, a disabled function or erratic readings from the same module.
U3015 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3015
- Warning lamp or message for the system run by the affected module
- Function cut back or switched off, often depending on load or moisture
- Stored together with other supply or ground codes of the same module
Common causes of U3015
- Most likelyCorroded or loose ground eyelet at the body or frame point
- PossibleChafed or broken ground wire between module and ground point
- PossibleSpread or corroded ground pin in the module connector
- Less likelyInternal fault in the module's ground measurement
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Module ground cGround strap
What each part of U3015 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 15 | The exact fault in that area. |
What to do next
- Note U3015 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 U3015
What does U3015 mean?
U3015 means "Control Module Ground C". U3015 reports that the third ground path of a module, labelled C, is missing or no longer plausible. It is a generic code, so it means the same on every make.
Is it safe to drive with U3015?
Drive gently and only to a workshop. With U3015 the car can go into limp mode (reduced power) to protect itself.
Will U3015 fail an emissions test?
U3015 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 U3015 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U3015 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.