What Does C1243 Mean?
The ABS control module has detected an open circuit in the left rear ABS outlet valve coil. The valve coil winding or its connecting wires have an infinite resistance break, preventing the module from energizing the valve to release brake pressure at the left rear wheel during ABS events.
Safety Warning
The left rear wheel ABS outlet valve cannot function. ABS braking at this wheel is disabled, increasing risk of wheel lockup and loss of control during emergency stops. Repair immediately.
Common Causes
40%
Open-circuited outlet valve coil winding inside the ABS hydraulic control unit from thermal degradation
25%
Broken wire in the internal connection between ABS module circuit board and hydraulic unit valve coil
20%
Corroded or separated connector between the electronic control module and hydraulic modulator
15%
Cracked circuit board trace inside the ABS module on the outlet valve driver circuit
Diagnostic Steps
1
Step 1: Measure left rear outlet valve coil resistance at the ABS module connector. An OL (infinite) reading confirms the open circuit. Normal range is typically 3-6 ohms.
2
Step 2: If accessible, measure resistance directly at the valve coil terminals on the hydraulic unit to isolate whether the open is in the coil or the wiring between module and coil.
3
Step 3: Inspect the connector between the ABS electronic module and the hydraulic modulator assembly for corrosion, loose pins, or physical damage.
4
Step 4: Check for thermal damage signs on the ABS module or modulator that might indicate overheating caused the coil open.
5
Step 5: Replace the failed component (hydraulic modulator if coil is open, module if wiring/board is failed). Perform ABS brake bleed after replacement. Clear codes and test drive.
Estimated Repair Cost
$300 - $1,200
Parts + labor, varies by vehicle and location
The ABS control module has detected an open circuit in the left rear ABS outlet valve coil. The valve coil winding or its connecting wires have an infinite resistance break, preventing the module from energizing the valve to release brake pressure at the left rear wheel during ABS events.
The most common cause of C1243 (ABS Outlet Valve Coil LR Circuit Open) is: Open-circuited outlet valve coil winding inside the ABS hydraulic control unit from thermal degradation
Typical repair costs for C1243 range from $300 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The left rear wheel ABS outlet valve cannot function. ABS braking at this wheel is disabled, increasing risk of wheel lockup and loss of control during emergency stops. Repair immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1243 to identify the root cause.
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Quick Info
Category
Chassis
System
Anti-lock Brake System (ABS)
Difficulty
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