OBD-II trouble code
C0080: Left Rear ABS Solenoid #1 Circuit Malfunction
The ABS module detected a fault in the left rear ABS solenoid #1 (inlet/isolation valve) circuit. ABS, traction, and stability control are disabled, but your normal (base) brakes still work.
Quick facts
- System
- Chassis
- Category
- ABS / Hydraulic
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $250 – $1,000
- DIY difficulty
- Advanced DIY
What does C0080 mean?
Within the anti-lock brake hydraulic unit, each wheel circuit uses two electrically controlled solenoid valves to modulate brake pressure during ABS, traction control, and stability control events. Solenoid #1 is the inlet (isolation) valve that holds or blocks pressure to that wheel, working with solenoid #2, the outlet (dump) valve that releases pressure. The electronic brake control module (EBCM) supplies these valves battery voltage when the key is on and controls each one by grounding its circuit. C0080 sets when the module sees that the left rear solenoid #1 circuit is not responding correctly to its commands — the circuit is open, shorted, or drawing current outside the expected range.
Because the module can no longer trust that it can control pressure at the left rear wheel, it disables the electronically managed brake functions and turns on the ABS, traction, and stability (ESC) warning lights. Your ordinary hydraulic brakes are not affected — the pedal stops the car normally — but anti-lock, traction, and stability assistance are switched off until the fault is repaired. Note that some vehicles route both rear wheels through a shared rear channel, so a rear solenoid fault can affect rear-wheel pressure management specifically; either way, base braking is retained.
On nearly all modern vehicles the ABS solenoid valves are integral to the hydraulic control unit / EBCM assembly and are not sold or replaced individually, so a genuine internal valve or driver-circuit failure usually means replacing or rebuilding the module. Before condemning the unit, verify the wiring, the main connector at the hydraulic unit, and the module's power and ground — corrosion, a backed-out terminal, or low system voltage can set solenoid-circuit codes without an internal defect. C0080 is common on GM vehicles, but the exact rear-valve numbering and channel layout vary by manufacturer and system, so confirm the definition in service data for your specific vehicle before buying parts.
Common causes
- Failed internal left rear #1 (inlet/isolation) solenoid valve within the EBCM/hydraulic unit
- Corroded, loose, or damaged main connector at the hydraulic control unit
- Chafed, open, or shorted wiring in the solenoid circuit
- Low battery or system voltage affecting the module
- Corroded or high-resistance EBCM ground
- Faulty EBCM (internal valve-driver circuit failure)
Symptoms
- ABS warning light on
- Traction control and stability control (ESC) warning lights on
- ABS, traction, and stability features disabled
- Normal (base) braking still works
- Warning lights may be intermittent if the cause is a connection or voltage issue
Diagnostic steps
- 1.Scan the ABS module and record C0080 plus any companion solenoid or relay codes (C0085, C0060, C0070, C0121 often appear together).
- 2.Load-test the battery and confirm charging-system voltage — low voltage can trigger solenoid-circuit codes.
- 3.Inspect the main connector at the hydraulic control unit for corrosion, backed-out terminals, or moisture intrusion.
- 4.Perform voltage-drop tests on the EBCM power feed and ground, and check the ABS system fuse.
- 5.Clear the code and note whether it returns immediately or only intermittently; an intermittent set points to wiring/connection or voltage rather than the module.
- 6.If power, ground, connector, and wiring are all good and the code persists, the internal solenoid valve is the likely fault and the EBCM/hydraulic unit typically needs replacement or rebuild with programming.
Repair cost
$250 – $1,000
The ABS solenoid valves are integral to the hydraulic control unit / EBCM and are not serviceable individually, so a confirmed internal solenoid failure usually means module replacement or rebuild plus programming, commonly $400-$1,000 at a shop. Mail-in module rebuild services can lower the parts cost to roughly $150-$300. If the true cause is a corroded connector, damaged wiring, a bad ground, or low voltage, the repair is far cheaper — verify those first.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with abs module / ebcm replacement preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.