ABS / traction light on: Codes, Causes & Fixes
When the ABS or traction control light is on, the anti-lock and stability functions are usually disabled while normal braking still works – so allow extra stopping distance, especially on wet or icy roads. The most frequent causes are a wheel speed sensor, its wiring or a dirty or cracked tone ring, followed by low brake fluid and ABS module faults. If the red brake warning light is on as well, or the pedal feels soft, stop driving and have the brakes checked.
65Codes
3.0Average severity
12%High or critical
15%DIY-friendly
Severity distribution
Most viewed
C0035
Chassis
The ABS module lost a valid signal from the driver-side front wheel speed sensor.
Moderate
P0562
Powertrain
The engine computer sees too little supply voltage – usually a charging, battery or ground…
Moderate
U0073
Network
A module saw so many errors on CAN bus A that it shut off its own transmitter.
High
U0121
Network
Other modules stopped receiving data from the ABS module, so ABS and stability control are off.
Moderate
U0122
Network
Other modules lost contact with the stability control computer, so ESC and traction control…
Moderate
P0500
Powertrain
The engine computer lost its vehicle speed signal – speedometer, shifting and cruise control…
Moderate
All codes (8)
C0021
Chassis
The brake module thinks the power brake booster isn't giving the assist it should. Check pedal…
High
C1252
Toyota · Chassis
The brake pressure pump ran far longer than normal without reaching or holding its target…
High
C1256
Toyota · Chassis
The brake system's high-pressure accumulator is below its minimum, so power brake assist can't…
Critical
C1391
Toyota · Chassis
The hybrid brake system is losing stored hydraulic pressure internally, so the pump keeps…
High
P2504
Powertrain
The charging system is overcharging – too much voltage can boil the battery and damage…
High
U0001
Network
A module found the high-speed CAN network itself misbehaving, not just one silent module.
High
U0073
Network
A module saw so many errors on CAN bus A that it shut off its own transmitter.
High
U0418
Network
Brake-control data such as pedal position or brake-assist status looks implausible to another…
High