P229B code meaning
Fuel Pressure Regulator B Exceeded Control Limits - Pressure Too High
Powertrain system Generic code P22xx codes Check engine light
What P229B means
P229B flags rail pressure that stays above target while fuel pressure regulator B should be holding it. GM's 2018 diesel table, where regulator B is the rail pressure regulator valve, runs this check with the valve in closed-loop control and under the same enable conditions as P229A (fuel level, ambient pressure and temperature), mirroring the overpressure test P228D of the metering unit, and rates it Type B. A valve that sticks closed or cannot open far enough, a drive signal that keeps it energised, or a rail pressure sensor reading high are the classic causes. If pressure keeps climbing to the absolute ceiling, P2293 follows. P229A is the deficit case, P228D the same fault seen through regulator A.
P229B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P229B
- Check engine light
- Harder combustion noise
- Reduced power in some cases
Common causes of P229B
- Most likelyRail pressure regulator valve sticking closed
- PossibleRail pressure sensor reading too high
- Less likelyValve drive signal stuck on (wiring or module)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel pressure regulator
What each part of P229B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 2 | Area: fuel and air metering (injector circuit). |
| 9B | The exact fault in that area. |
What to do next
- Note P229B 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 P229B
What does P229B mean?
P229B means "Fuel Pressure Regulator B Exceeded Control Limits - Pressure Too High". P229B flags rail pressure that stays above target while fuel pressure regulator B should be holding it. It is a generic code, so it means the same on every make.
Is it safe to drive with P229B?
Drive gently and only to a workshop. With P229B the car can go into limp mode (reduced power) to protect itself.
Will P229B fail an emissions test?
Yes, it can. P229B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P229B to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P229B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.