C0020
ABS pump motor control circuit fault
Severity: Inspect soonABS, traction and stability control codes
Anti-lock brakes stop the wheels locking under hard braking, and the same control module usually runs traction control and electronic stability control, which brake single wheels and can cut engine power to keep the car pointed where the driver steers. It all depends on a speed sensor at each wheel plus a pump and valve block that adjust brake pressure. When the module finds a fault it turns on a yellow ABS or stability warning and usually switches those functions off.
How these codes differ
- The warning lights split the problem before any code is read. US rules give the anti-lock system its own yellow ABS light for electrical faults, separate from the red brake light, which is for a serious loss of brake fluid or pressure. A yellow ABS or stability light alone usually means the anti-lock and stability help is off; a red brake light means the basic brakes themselves may be affected and the car should not be driven until checked.
- Wheel speed sensor codes are the most common group. A circuit-type code (open, short, no signal) points to the sensor, its connector or its wiring, which often runs near the wheel where it gets damaged. A signal or plausibility code (one wheel reading differently from the others, or an erratic signal) points instead to dirt on the sensor, a damaged encoder or tone ring, or a worn wheel bearing that lets the gap change.
- Pump motor, valve, pressure sensor and module codes are about the hydraulic unit and its electronics rather than the wheels. They concern the module and hydraulic unit itself, which is a brake part and belongs with a professional.
- Most ABS codes are manufacturer-specific (C1xxx and C2xxx), so the same number can mean different things on different makes. Read the code with a scan tool that can talk to the ABS module and use the carmaker's definition.
- Stability control needs inputs beyond wheel speed: a yaw rate sensor, steering input and engine torque control. A stability-only warning can therefore come from a steering angle sensor or an engine-side fault, not just the brakes.
Codes that show up together
- A wheel speed sensor code together with a speedometer, transmission or engine complaint: the ABS module passes wheel speed on to the engine, transmission and other systems, so one bad wheel signal can show up in several places. Fix the wheel speed fault first.
ABS, traction and stability control codes
C1185
ABS power relay output circuit failure (Ford)
Severity: Inspect soonC1194
ABS left front outlet valve circuit fault (Ford)
Severity: Inspect soonC1198
ABS left front inlet valve circuit fault (Ford)
Severity: Inspect soonC1210
ABS outlet valve coil circuit failure, right front (Ford)
Severity: Inspect soonC1214
ABS inlet valve coil circuit failure, right front (Ford)
Severity: Inspect soonC1223
ABS control system malfunction seen by stability control (Toyota)
Severity: Inspect soonC1242
ABS left rear outlet valve circuit fault (Ford)
Severity: Inspect soonC1246
ABS right rear outlet valve circuit fault (Ford)
Severity: Inspect soonC1247
Brake pedal stroke sensor fault (Toyota)
Severity: Inspect soonC1252
Hybrid brake booster or actuator fault (Toyota, Lexus) or vacuum pump control circuit (Chrysler, Jeep, Ram)
Severity: Inspect soonC1253
Hybrid brake booster or actuator fault, internal brake fluid leak (Toyota, Lexus)
Severity: Inspect soonC1254
ABS right rear inlet valve circuit fault (Ford)
Severity: Inspect soonC1256
Hybrid brake booster or actuator fault, internal brake fluid leak (Toyota, Lexus)
Severity: Inspect soonC1391
Hybrid brake booster or actuator fault, internal brake fluid leak (Toyota, Lexus)
Severity: Inspect soonC2200
Anti-lock brake module internal fault (Ram, Dodge)
Severity: Inspect soonP25A2
Brake control module has asked for the check engine light
Severity: Inspect soonC1203
Skid control ECU to engine computer communication malfunction (Toyota)
Severity: Inspect soonC121C
Torque request signal denied, stored in the ABS module (Chrysler, Jeep, Ram)
Severity: Inspect soonC1241
Low or high power supply voltage to the skid control (ABS/VSC) ECU (Toyota)
Severity: Inspect soonC1963
Stability control inhibit warning, stored in the ABS module (Ford)
Severity: Inspect soonC0021
Brake booster performance or signal fault (Dodge and Jeep)
Severity: Inspect soonC0040
Right front wheel speed sensor circuit (GM) or brake lamp switch (Honda)
Severity: Inspect soonC0051
Steering wheel position (angle) sensor signal fault
Severity: Inspect soonC0242
Engine computer reporting a fault that blocks traction control
Severity: Inspect soonC1235
Right rear wheel speed sensor input missing (Ford)
Severity: Inspect soonC1513
Brake switch circuit fault (Hyundai)
Severity: Inspect soonC1A16
Radar sensor blocked or obstructed (Nissan)
Severity: Inspect soonC006C
Can-Am Ryker yaw rate or steering angle sensor fault
Severity: Inspect soonC0196
Stability system sees a sensor or motion fault (GM)
Severity: Inspect soonC0210
Right rear wheel speed sensor circuit or signal fault
Severity: Inspect soonC0800
GM chassis control module voltage fault
Severity: Inspect soonC1130
ABS control unit not recognising an engine computer signal (Nissan and Infiniti)
Severity: Inspect soonC1201
Toyota engine control communication fault reported by the skid control system
Severity: Inspect soonC1231
Toyota skid control (ABS/VSC) fault, tied to the steering angle sensor input
Severity: Inspect soonC1234
ABS wheel sensor output failure (Ford)
Severity: Inspect soonC1237
Primary brake pressure sensor signal (Hyundai) or rear wheel speed sensor (Ford)
Severity: Inspect soonC1310
Toyota active brake booster solenoid fault
Severity: Inspect soonC1480
Right front wheel brake pressure control fault (Ford and Mercury hybrids)
Severity: Inspect soonC0035
Left front wheel speed sensor circuit fault (GM)
Severity: Severity not verifiedC0131
Brake pressure circuit fault (GM)
Severity: Severity not verifiedC1446
Brake switch circuit failure (Ford)
Severity: Severity not verifiedC0037
Left rear wheel speed sensor circuit fault
Severity: Inspect soonC003A
Right rear wheel speed sensor circuit fault
Severity: Inspect soonC0161
ABS computer does not trust the brake pedal switch signal
Severity: Inspect soonC0186
Sideways (lateral) acceleration sensor signal faulty or not believable
Severity: Inspect soonC0215
Left rear wheel speed sensor circuit fault (Toyota)
Severity: Inspect soonC0265
ABS computer reports a fault in its relay circuit
Severity: Inspect soonC0277
Brake pedal position sensor fault (GM)
Severity: Inspect soonC0287
Stability computer flags a fault in a motion-sensing signal circuit
Severity: Inspect soonC0550
A chassis control module reports an internal fault
Severity: Inspect soonC1116
Stop lamp switch circuit fault in the ABS system (Nissan)
Severity: Inspect soonC1236
Left rear wheel speed sensor input missing (Ford)
Severity: Inspect soonC1300
ABS / skid control ECU malfunction (Toyota)
Severity: StopP050F
Not enough vacuum for the brake booster
Severity: Inspect soonC1226
Excessive wheel speed variation at one front wheel (GM)
Severity: Inspect soonC159C
Trailer brake control switch fault (Chevrolet, GMC)
Severity: Inspect soonC0050
Right rear wheel speed sensor circuit fault (GM)
Severity: Severity not verifiedC1221
Left front wheel speed sensor signal is zero (Chevrolet)
Severity: Severity not verifiedC1233
On Chevrolet and Buick, right front wheel speed sensor circuit open or shorted
Severity: Severity not verifiedC1345
Brake linear solenoid valve offset learning not done (Toyota)
Severity: Severity not verifiedC0031
Left front wheel speed sensor circuit fault (Ford and Lincoln)
Severity: Severity not verifiedC0045
Left rear wheel speed sensor circuit fault (GM)
Severity: Severity not verifiedP0555
Brake booster pressure sensor circuit fault
Severity: Inspect soonP258B
Brake vacuum pump not performing as the computer expects
Severity: Inspect soon
Sources and review
- 49 CFR 571.135, Standard No. 135: Light vehicle brake systems
- 49 CFR 571.126, Standard No. 126: Electronic stability control systems for light vehicles
- Check and change ABS and wheel speed sensors
- Diagnostic Trouble Codes Explained: How to Manage DTCs
- 2003 Acura MDX Owner's Manual: Instruments and Controls, indicator lights
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error