Brake system control module (ABS module) codes

How its codes differ

• C2200 is the module reporting its own internal fault. Chrysler and Ram bulletins fix some cases with new module software; otherwise the module may need replacing.
• C1194, C1198, C1242, C1246 and C1254 are valve circuit codes in the Ford-style numbering. Mazda's manual for the same numbers names a fault in the valve circuits inside the control unit, and C1185 (the module's internal power relay) often appears alongside them on the Windstar.
• P25A2 is the brake module asking the engine computer to light the check engine light. GM bulletins tie it to low voltage, wiring, or a brake module or hydraulic fault, sometimes with a hard or spongy pedal.
• U0121 and U0415 are stored by other modules: U0121 means they lost contact with the ABS module (wiring, power and ground come first), and U0415 means it sent invalid data, often because it is reporting a fault of its own.
• B1342 on some Ford and Lincoln models, and C1247 on Toyota models with a skid control ECU, can also point to the brake module, but each has other causes to rule out first.

Codes

• B1342

  Control module internal fault (Ford, Lincoln)

  Severity: Inspect soon

• C1185

  ABS power relay output circuit failure (Ford)

  Severity: Inspect soon

• C1194

  ABS left front outlet valve circuit fault (Ford)

  Severity: Inspect soon

• C1198

  ABS left front inlet valve circuit fault (Ford)

  Severity: Inspect soon

• C1242

  ABS left rear outlet valve circuit fault (Ford)

  Severity: Inspect soon

• C1246

  ABS right rear outlet valve circuit fault (Ford)

  Severity: Inspect soon

• C1247

  Brake pedal stroke sensor fault (Toyota)

  Severity: Inspect soon

• C1254

  ABS right rear inlet valve circuit fault (Ford)

  Severity: Inspect soon

• C2200

  Anti-lock brake module internal fault (Ram, Dodge)

  Severity: Inspect soon

• P25A2

  Brake control module has asked for the check engine light

  Severity: Inspect soon

• U0121

  Lost communication with the anti-lock brake (ABS) module

  Severity: Inspect soon

• U0415

  A module received invalid data from the anti-lock brake (ABS) module

  Severity: Inspect soon

Signs it's failing

• ABS warning light, sometimes with the traction or stability control light
• Red brake warning light together with the ABS light
• Hard or spongy brake pedal or loss of brake assist on some GM trucks with P25A2 or P0606
• ABS or traction control not working when needed, or working when it should not
• U0121 or U0415 stored in other modules

How to test it

1. Brakes are safety-critical. If the red brake warning stays on with the parking brake released, or the pedal feels low, hard or spongy, do not drive; have the vehicle towed or inspected. With only the yellow ABS light on, normal braking still works but anti-lock does not. (Low risk)

2. With the engine off and cold, look at the brake fluid level in the reservoir and for wet spots or leaks, without opening any brake lines. (Low risk)

3. Read codes in all modules with a scan tool and have the battery and charging system tested; low voltage can make the brake module set false codes. (Low risk)

4. Ask a dealer whether your VIN has a recall, software update or bulletin for the brake code. (Low risk)

5. Brake module diagnosis, software updates and replacement, and the brake bleeding that may go with them, are jobs for a qualified shop. (Best left to a shop)

   Warning: Mistakes on the brake system can cause brake failure and a crash. A replacement module must be programmed with the right calibration, and on some vehicles the brakes are bled and sensors calibrated before it works correctly.

After the repair

• Confirm the shop programmed the new module and completed any brake bleed and sensor calibration the maker requires.
• Check that the ABS and red brake warnings go out after start-up and that the pedal feels firm before driving.
• Have codes cleared in all modules and recheck after a road test.