Chassis, generic

C0201 Brake Fluid Level Switch Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Searches of J2012 tables, NHTSA bulletins and maker indexes found no trace of C0201, so no vehicle use can be shown; GM files its low-fluid input under C0128. The title concerns the wiring of the float switch fitted to the master cylinder reservoir. On the Saab 9-5 that switch sits in the filler cap: a float with two contacts closes once the level has dropped to about two thirds and grounds the warning lamp, which the cluster also lights for 3 s at key-on as a bulb check. A Nabco/Nissan patent places a reed switch under the reservoir floor, worked by a magnet in the float, with a push-down test. Under FMVSS 135 the driver must be warned once any chamber drops under the maker's safe mark or one quarter of its capacity. A circuit code points to a broken lead, a corroded plug or an internally shorted switch.

Likely causes

Corroded or loose connector at the reservoir cap or switch
Level switch shorted or open internally, float stuck
Chafed wiring between switch and module
Actually low fluid from worn pads or a leak

Symptoms

  • Red brake warning lamp on or flickering
  • Low-fluid message although the reservoir is full

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–150
Time0.2–1 h

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

Parts involved

brake fluid level switchbrake fluid reservoirabs control module

Related codes

C0128C0049C004B

References: saabwisonline.com, patents.google.com, law.cornell.edu.