Chassis, generic

C0304 Outlet Valve Front Right Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

No public source confirms C0304; searches of the J2012 tables at hand, of GM's keyword bulletin PIP5094, of AA1Car and of the NHTSA bulletin index came up empty. The title concerns the front right outlet valve, the part that bleeds pressure off that caliper when the wheel starts to lock. In the TRW brake system of Saab's 2011 9-5, the EBC450, the module first holds pressure by closing the inlet valve and only then opens this dump valve, sending fluid into the accumulator, from where the pump returns it. A valve that will not open lets the front right wheel lock; a valve that does not reseal drains pressure, gives a long pedal and can make the car pull left. Saab's ESP version uses the same valves for stability braking, so the fault disables ABS and ESP alike.

Likely causes

Outlet valve not resealing because of dirt in the seat
Valve coil or brake module output stage defective
Accumulator or return pump unable to take the released fluid

Symptoms

  • ABS and stability control warning lamps on
  • Long brake pedal or front right wheel locking

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,500
Time1–3 h

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

Parts involved

rf abs outlet valveabs hydraulic blockabs control module

Related codes

C0303C0302C0309

References: saabwisonline.com, saabwisonline.com, bosch-mobility.com.