What Does C1266 Mean?
The ABS module has detected a malfunction in the left rear outlet (dump) valve solenoid. This valve is responsible for releasing hydraulic pressure from the left rear brake during ABS cycling. When malfunctioning, the ABS cannot properly release pressure on the left rear wheel, potentially causing it to lock during anti-lock braking events.
Common Causes
40%
Failed left rear outlet valve solenoid in the ABS hydraulic modulator
25%
Internal wiring or connection fault to the outlet solenoid driver
20%
Contaminated brake fluid causing the outlet valve to stick closed
10%
ABS module electronic driver circuit failure for left rear outlet
5%
Poor module ground preventing proper solenoid actuation
Diagnostic Steps
1
Use bi-directional scan tool control to command the left rear outlet valve solenoid on and off — listen for clicking at the ABS hydraulic modulator.
2
Measure the left rear outlet solenoid resistance at the ABS module connector — expect 3-6 ohms. Open or shorted readings indicate a failed solenoid coil.
3
Verify ABS module power supply and ground connections. Check for voltage drop across ground circuit under load — should be below 100 mV.
4
Inspect brake fluid condition. Discolored, contaminated, or old fluid can cause internal valve corrosion. Perform a complete brake fluid flush if warranted.
5
If electrical and fluid tests pass but the code returns, the valve is mechanically seized and the ABS hydraulic modulator assembly requires replacement.
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The ABS module has detected a malfunction in the left rear outlet (dump) valve solenoid. This valve is responsible for releasing hydraulic pressure from the left rear brake during ABS cycling. When malfunctioning, the ABS cannot properly release pressure on the left rear wheel, potentially causing i...
The most common cause of C1266 (Left Rear Outlet Valve Solenoid Malfunction) is: Failed left rear outlet valve solenoid in the ABS hydraulic modulator
Typical repair costs for C1266 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS cannot properly release pressure on the left rear brake during anti-lock operation. The left rear wheel could lock during hard braking on slippery surfaces. Normal braking works fine. Drive carefully, avoid aggressive braking, and schedule repair soon.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1266 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
ABS / Traction Control
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
