ABS System Performance Problem
The ABS control module has detected a fault in the system performance.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The Anti-lock Braking System (ABS) control module is seeing a problem with how the brakes are working. It looks for things like wheel speed sensors and hydraulic pressure to make sure everything's functioning correctly.
What the computer is actually seeing
The ABS module monitors wheel speeds and pressures constantly. If it notices that the wheel speed (should be within 0-255 km/h) isn’t matching with the expected values compared to other wheels or the hydraulic pressure isn’t in the range of 50-200 psi, it will trigger this code.
What a healthy reading looks like
Expect wheel speeds to be within 10% of each other; hydraulic pressure should hold steady around 70 psi during normal operation.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check brake fluid level; it should be between the Minimum and Maximum marks. If low, refill and check for leaks.
- 22. Inspect wheel speed sensors for damage or debris. Make sure wiring is intact; if damaged, repair or replace the sensor.
- 33. Use a scan tool to check wheel speed sensor readings. All wheels should show speed readings during a test drive; if one is stuck at 0, replace that sensor.
- 44. Check the ABS module connectors for corrosion or loose connections, clean or repair as needed.
- 55. Clear the code and take the vehicle for a test drive to see if the code returns.
Common causes
- Faulty wheel speed sensor
- Damaged wiring or connectors
- Hydraulic pump failure
- Low brake fluid level
- Corroded ABS module connection
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with C1120 code?
Yes, but be cautious. ABS may not function, leading to wheel lock-up in slippery conditions.
Will the code come back after clearing it?
It may come back if the underlying issue isn't fixed, so thorough diagnostics is essential.
How does C1120 relate to other brake issues?
Since it involves ABS, any brake system issues like worn pads or low fluid might trigger it; address those first.
Working a real vehicle right now?
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