U3019 code meaning
Control Module Input Power Circuit B/C Correlation
Network system Generic code U30xx codes Check engine light
What U3019 means
U3019 pairs the second and third supply of a module and reports that they drift apart. The one published use comes from GM's electric brake booster module in the 2016 and 2018 hybrid tables (16OBDG02, 18OBDG01). There, one voltage sensor watches the booster circuit supply and a second one the supply of the motor driver; the module divides the two readings and sets U3019 when the ratio rises above 1.321 or falls below 0.766 for 2 s while running or shutting down. GM describes this as a check for drift of the voltage divider, so besides a weak feed a measuring fault inside the module is a real candidate. The code is Type A, meaning MIL on the first trip, and it passes after about 5 s with ignition on. Because the booster supports braking, expect a brake warning and possibly reduced assist.
U3019 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3019
- MIL and brake system warning on the first trip
- Reduced or harder brake pedal assist
- Often stored with input power low or high codes of the same module
Common causes of U3019
- PossibleVoltage loss on one feed from a corroded fuse, terminal or splice
- PossibleDrift of the voltage divider or sensor inside the module
- Less likelyMotor driver supply sagging under load from a faulty booster motor stage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Module power bModule power cBrake booster module
What each part of U3019 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 19 | The exact fault in that area. |
What to do next
- Note U3019 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 U3019
What does U3019 mean?
U3019 means "Control Module Input Power Circuit B/C Correlation". U3019 pairs the second and third supply of a module and reports that they drift apart. It is a generic code, so it means the same on every make.
Is it safe to drive with U3019?
Drive gently and only to a workshop. With U3019 the car can go into limp mode (reduced power) to protect itself.
Will U3019 fail an emissions test?
U3019 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 U3019 to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U3019 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.