Powertrain, generic (extended)

P229B Fuel Pressure Regulator B Exceeded Control Limits - Pressure Too High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Rail pressure regulator valve sticking closed
Rail pressure sensor reading too high
Valve drive signal stuck on (wiring or module)

Symptoms

  • Check engine light
  • Harder combustion noise
  • Reduced power in some cases

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,500
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel pressure regulator

Related codes

P229AP228DP2293P0088

References: gsi.ext.gm.com, law.cornell.edu.