Reference meaning
What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
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A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Scan worksheet →Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
U0121-00Lost Communication With Anti-lock Brake System (ABS) Control Module
U0121-00Lost Communication With Anti-Lock Brake System (ABS) Control Module
U0121LOSS OF COMMUNICATION WITH EBCM
Manufacturer communications
62Original wording in English
CHRYSLER
Flash: Anti-Lock Brakes (ABS) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Code (DTC): ● **C151D-00 - Tire Pressure Sensor Location Undetermined.** ● U0121-00 - Lost Communication With Anti-lock Brake Sy…
CHRYSLER
Flash: Anti-Lock Brakes (ABS) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U0121-00 - Lost Communication With Anti-lock Brake System (ABS) Control Module. ● U1110 - Lost Vehicle Speed Mes…
JEEP
Not applicable to vehicles built for US market. Multiple Systems Repair Bundle Campaign Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● U11E3-00 - TCM Lost Communication With ESM On DPT CAN. ● B15A1-00 - Med…
CHRYSLER
Vehicle Will Not Shift From Park. Antilock Brake System (ABS) Light On In Cluster. U0121, U1110, U120C Diagnostic Trouble Codes (DTCs) Set. Discussion: If a vehicle has a complaint of will not shift from park and the below DTCs are set, follow the steps below prior to making any repairs. U0121-00-LOST COMMUNICATION WITH ANTI-LOC…
Check vehicle applicability
796A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Audi | A4 ↗ | 2010 |
| Audi | A4 ↗ | 2009 |
| Audi | A4 ALLROAD ↗ | 2014 |
| Audi | A4 ALLROAD ↗ | 2013 |
| Audi | A4 AVANT ↗ | 2012 |
| Audi | A4 AVANT ↗ | 2011 |
| Audi | A5 ↗ | 2014 |
| Audi | A5 ↗ | 2013 |
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.