C0304 code meaning
Outlet Valve Front Right Performance
What C0304 means
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.
C0304 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0304
- ABS and stability control warning lamps on
- Long brake pedal or front right wheel locking
Common causes of C0304
- PossibleOutlet valve not resealing because of dirt in the seat
- PossibleValve coil or brake module output stage defective
- Less likelyAccumulator or return pump unable to take the released fluid
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Rf ABS outlet valveABS hydraulic blockABS control module
What each part of C0304 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 04 | The exact fault in that area. |
What to do next
- Note C0304 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 C0304
What does C0304 mean?
C0304 means "Outlet Valve Front Right Performance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with C0304?
Drive gently and only to a workshop. With C0304 the car can go into limp mode (reduced power) to protect itself.
Will C0304 fail an emissions test?
C0304 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 C0304 to fix?
Difficulty: hard. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will C0304 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.