What Does C1251 Mean?
The ABS control module has detected an open circuit in the left rear ABS inlet valve coil. The coil winding or its connecting circuitry has an electrical break, preventing current flow to the valve solenoid. Without the ability to energize this valve, the ABS cannot block additional pressure buildup at the left rear wheel during anti-lock activation.
Safety Warning
ABS inlet valve at the left rear is non-functional. Anti-lock braking capability is degraded, increasing the risk of wheel lockup and loss of control. Repair immediately.
Common Causes
40%
Open winding in the left rear inlet valve coil from thermal fatigue or manufacturing defect
25%
Broken wire or cold solder joint in the connection between ABS module and hydraulic unit valve coil
20%
Separated or corroded connector pin at the module-to-modulator interface
15%
Cracked circuit board trace on the valve driver output inside the ABS electronic module
Diagnostic Steps
1
Step 1: Measure left rear inlet valve coil resistance at the ABS module connector. An OL reading confirms the open circuit. Normal is typically 3-6 ohms.
2
Step 2: If the module and modulator are separable, measure the coil resistance directly at the modulator terminals to isolate the open to either the coil or the module wiring.
3
Step 3: Inspect the module-to-modulator connector pins for corrosion, green deposits, or recessed pins that would prevent contact.
4
Step 4: Check for any signs of overheating on the ABS module or modulator housing that could indicate thermal damage to the coil.
5
Step 5: Replace the component with the open circuit (modulator for failed coil, module for broken trace). Bleed the ABS system, clear codes, and verify all valve resistances are in spec.
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 inlet valve coil. The coil winding or its connecting circuitry has an electrical break, preventing current flow to the valve solenoid. Without the ability to energize this valve, the ABS cannot block additional pressure buildup...
The most common cause of C1251 (ABS Inlet Valve Coil LR Circuit Open) is: Open winding in the left rear inlet valve coil from thermal fatigue or manufacturing defect
Typical repair costs for C1251 range from $300 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS inlet valve at the left rear is non-functional. Anti-lock braking capability is degraded, increasing the risk of wheel lockup and loss of control. Repair immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1251 to identify the root cause.
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Quick Info
Category
Chassis
System
Anti-lock Brake System (ABS)
Difficulty
Type
Manufacturer
Recommended Tools
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