How much does it cost to fix U0121?

Typical repair cost is $100–$800.

U0121 — Lost Communication with ABS Control Module

High Severity · Network

OBD-II code U0121 means your vehicle's ECU detected: Lost Communication with ABS Control Module. Below: causes, step-by-step fixes, and repair cost — free, no signup needed.

High severity — do not ignore. Get a diagnosis promptly to avoid further engine damage.

Typical Repair Cost

$100–$800

Parts + labor, national average

Severity

High

Address as soon as possible

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Common Causes of U0121

Failed ABS module
CAN bus fault
Wiring

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How to Fix Code U0121

Check ABS module power/ground

Inspect CAN bus wiring

Test ABS module

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FAQ — Code U0121

What does OBD-II code U0121 mean?

U0121 means your vehicle's onboard computer detected: Lost Communication with ABS Control Module. This is a high-severity code in the Network category.

How much does it cost to fix code U0121?

Typical repair cost for U0121 is $100–$800 including parts and labor. Costs vary by vehicle make, model, and location. A free scan at AutoZone or O'Reilly is a good first step.

Can I drive my car with code U0121?

Code U0121 is high severity. Avoid long drives until diagnosed — continued driving can cause additional engine damage.

What are the most common causes of U0121?

The most common causes are: Failed ABS module, CAN bus fault, Wiring. Always start with the cheapest diagnosis step before replacing parts.

Will code U0121 clear itself?

Code U0121 will clear itself after the underlying issue is fixed and the ECU completes several successful drive cycles. Clearing it without fixing the root cause only masks the problem temporarily.

Is U0121 showing on your car?

Enter your VIN for a free vehicle-specific report — recalls, specs, and market value. No signup required.

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U0100Lost Communication with ECM/PCM U0101Lost Communication with TCM U0155Lost Communication with Instrument Panel...

OBD-II code data is based on SAE J2012 standards and general repair industry data. Repair costs are national averages and vary by vehicle, location, and shop. Always consult a qualified mechanic for a diagnosis specific to your vehicle.