What Does C1257 Mean?
The ABS control module has detected a short to ground on the right rear ABS inlet valve coil circuit. The driver circuit for this solenoid valve has an unintended low-resistance path to vehicle ground, causing excessive current draw and preventing proper valve control during ABS braking events at the right rear wheel.
Safety Warning
ABS inlet valve control is lost at the right rear wheel. Brake modulation during ABS events is compromised, and the ground short may cause additional electrical damage. Repair immediately.
Common Causes
35%
Right rear inlet valve coil insulation failure allowing winding-to-body ground contact
25%
Internal wiring ground fault inside the ABS module housing from pinched or degraded wire
25%
Brake fluid intrusion from the modulator into the electronic module causing conductive ground paths
15%
Corrosion at the module connector creating an unintended ground path between pins
Diagnostic Steps
1
Step 1: Separate the ABS module from the hydraulic modulator. Measure resistance from each right rear inlet valve coil terminal to the modulator body ground. Less than 10K ohms indicates a coil-to-ground short.
2
Step 2: Measure resistance from the module connector valve pins to module ground to isolate whether the short is in the module or the modulator.
3
Step 3: Inspect the module-modulator mating surface for brake fluid seepage, corrosion, or debris that could cause short circuits.
4
Step 4: If module internals are accessible, check the circuit board for corrosion, solder bridges, or damaged components near the right rear inlet driver.
5
Step 5: Replace the component with the ground short. Perform ABS brake bleed, clear codes, and verify all valve functions with bidirectional testing.
Estimated Repair Cost
$300 - $1,200
Parts + labor, varies by vehicle and location
The ABS control module has detected a short to ground on the right rear ABS inlet valve coil circuit. The driver circuit for this solenoid valve has an unintended low-resistance path to vehicle ground, causing excessive current draw and preventing proper valve control during ABS braking events at th...
The most common cause of C1257 (ABS Inlet Valve Coil RR Circuit Short To Ground) is: Right rear inlet valve coil insulation failure allowing winding-to-body ground contact
Typical repair costs for C1257 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 control is lost at the right rear wheel. Brake modulation during ABS events is compromised, and the ground short may cause additional electrical damage. Repair immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1257 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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