What Does C1242 Mean?
The ABS control module has detected a circuit failure in the left rear ABS outlet valve coil. The outlet valve releases brake pressure during ABS activation to prevent wheel lockup. A circuit failure means the module cannot command this valve, preventing proper ABS pressure release at the left rear wheel.
Safety Warning
ABS function is compromised at the left rear wheel. During emergency braking on slippery surfaces, the left rear wheel may lock up, potentially causing vehicle instability. Repair immediately.
Common Causes
40%
Failed ABS outlet valve coil in the hydraulic control unit with open or shorted windings
25%
Corroded or damaged internal wiring between the ABS module and hydraulic unit valve coils
20%
Poor solder joints or circuit board failure inside the ABS module affecting valve driver output
15%
Water or brake fluid contamination inside the ABS modulator assembly
Diagnostic Steps
1
Step 1: Measure the left rear outlet valve coil resistance at the ABS module connector pins per manufacturer specification (typical 3-6 ohms). Compare to the other outlet valve coil resistances.
2
Step 2: Check for shorts to ground and shorts to battery on both valve coil circuit wires. Both should read OL to ground and OL to battery voltage.
3
Step 3: Inspect the ABS hydraulic control unit for signs of brake fluid leaks, external corrosion, or physical damage that could affect the valve coils.
4
Step 4: If coil resistance is in spec and wiring checks pass, perform a functional test using a bidirectional scan tool to command the outlet valve on and listen for an audible click.
5
Step 5: If the valve fails to actuate with good circuit tests, the ABS hydraulic modulator assembly requires replacement. Clear codes and perform ABS bleed procedure after repair.
Estimated Repair Cost
$300 - $1,200
Parts + labor, varies by vehicle and location
The ABS control module has detected a circuit failure in the left rear ABS outlet valve coil. The outlet valve releases brake pressure during ABS activation to prevent wheel lockup. A circuit failure means the module cannot command this valve, preventing proper ABS pressure release at the left rear ...
The most common cause of C1242 (ABS Outlet Valve Coil LR Circuit Failure) is: Failed ABS outlet valve coil in the hydraulic control unit with open or shorted windings
Typical repair costs for C1242 range from $300 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS function is compromised at the left rear wheel. During emergency braking on slippery surfaces, the left rear wheel may lock up, potentially causing vehicle instability. Repair immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1242 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Chassis
System
Anti-lock Brake System (ABS)
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
