Chassis, generic

C0309 Outlet Valve Rear Right Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0309 is no part of any public J2012 table, and no manufacturer documents it as a valve code. GM does use it: it is among the keywords of PIP5094, and the GM code chart on AA1Car calls it Motor A/B Circuit High, a transfer case shift motor fault next to C0308 and C0310; that meaning rests on this single source. The title instead names the rear right outlet valve. It opens to let fluid out of the right rear caliper into the accumulator when that wheel tends to lock and stays shut otherwise. Saab's 9-5 checks each valve with a 20 ms pulse at every ignition-on, and a fault turns ABS, traction and stability control off. A valve stuck open would keep the right rear wheel from building pressure.

Likely causes

Rear right outlet valve not closing fully
Valve coil or brake module driver faulty
On GM 4WD trucks, transfer case motor circuit shorted to voltage (GM meaning of the number)

Symptoms

  • ABS and stability control warning lamps on
  • Weak braking at the right rear wheel

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

abs solenoid valve rrabs hydraulic blockabs control module

Related codes

C0307C0304C0302

References: static.nhtsa.gov, aa1car.com, saabwisonline.com, bosch-mobility.com.