ABS C1252: Left Rear Inlet Valve Short to Battery
The C1252 code is set when the ABS ECU detects battery voltage on the control circuit for the left rear inlet valve when it should be at ground or low state. This indicates a short to battery positive (B+) in the valve coil circuit, preventing proper hydraulic pressure modulation at that wheel. The fault can be internal to the ECU, in the wiring harness, or within the hydraulic control unit (HCU).
1. Commonly Affected Makes
2. Most Common Causes
3. Symptoms You Will Notice
- ABS warning light illuminated
- Possible loss of ABS function at left rear wheel
- Potential increase in stopping distance or unstable braking
4. Step-by-Step Diagnosis
Scan for additional ABS codes and check freeze frame data
Visually inspect the HCU connector and wiring for damage, corrosion, or shorts
Measure resistance of the left rear inlet valve coil (typically 2-10 ohms) and check for continuity to ground
Check for battery voltage on the valve control wire with the ignition on and engine off (should be near 0V when not commanded)
If wiring and valve are okay, suspect internal ECU failure and consider replacement or reprogramming
5. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive. The ABS system may not function properly, increasing the risk of wheel lockup and loss of control during hard braking. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
Repair costs typically range from $200 to $1,200 depending on the cause. A simple wiring repair may cost $200-$400, while replacing the ABS ECU or HCU can run $800-$1,200 including labor.