What does it mean?
C1702 is a Chassis (ABS, traction control, steering) fault code. It indicates: HECU Variant Code Fault .
Symptoms
- ABS and stability/traction warning lamps stay on
- ABS, traction control and stability control are switched off; plain hydraulic braking still works
- Hill hold, brake assist and electronic brake force distribution features unavailable
- Wheel speed data may be missing from other modules that rely on the HECU
- The code returns immediately after clearing until the unit is coded correctly
Likely causes
- ABS/ESP module replaced or reflashed without running the variant coding routine
- Wrong part number or software level fitted for the vehicle's brake and traction options
- Coding aborted by low battery voltage or a jump start during programming
- Option data mismatch between the HECU and the modules that broadcast vehicle configuration
- Corrupted internal memory (EEPROM) in the HECU
- Poor power feed or ground at the HECU so the coding data cannot be written or read reliably
How to fix it
- Scan all modules and compare the HECU part number and software level with the vehicle's build data
- Measure battery voltage and the HECU supply and ground before attempting any programming; low voltage aborts coding
- Inspect the HECU connector for corrosion, spread terminals and previous harness repairs
- Run the manufacturer variant coding / configuration routine with a capable scan tool
- Compare configuration data across modules and correct any option mismatch found
- If coding will not write while communication is good, the internal memory is faulty and the HECU must be replaced and coded
- After coding, perform steering angle and yaw sensor calibrations and road test to confirm the lamps go out