P229A code meaning
Fuel Pressure Regulator B Exceeded Control Limits - Pressure Too Low
Powertrain system Generic code P22xx codes Check engine light
What P229A means
P229A is the low-pressure control-limit check for fuel pressure regulator B. In GM's 2018 diesel table regulator B is the rail pressure regulator valve; while it governs the rail in closed loop, the ECM compares setpoint and measured pressure and flags a deficit beyond about 13 MPa, using the same 640-of-800-sample window and Type B rating as the metering unit check P228C. The test pauses at low fuel level, ambient pressure under 60 kPa or ambient temperature below −7 °C. A valve that no longer seals, internal injector leakage or a pump short of delivery create the deficit. GM is the only maker found documenting P229A publicly. P229B is the overpressure case, P228B the stage that forces a shutdown.
P229A at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P229A
- Check engine light
- Lack of power under load
- Longer cranking times
Common causes of P229A
- Most likelyRail pressure regulator valve leaking internally
- PossibleHigh-pressure pump delivering too little
- PossibleExcessive injector leak-off
- Less likelyRestricted low-pressure supply or clogged filter
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 P229A 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). |
| 9A | The exact fault in that area. |
What to do next
- Note P229A 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 P229A
What does P229A mean?
P229A means "Fuel Pressure Regulator B Exceeded Control Limits - Pressure Too Low". P229A is the low-pressure control-limit check for fuel pressure regulator B. It is a generic code, so it means the same on every make.
Is it safe to drive with P229A?
Drive gently and only to a workshop. With P229A the car can go into limp mode (reduced power) to protect itself.
Will P229A fail an emissions test?
Yes, it can. P229A 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 P229A to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P229A clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.