C1110 — ABS Power Relay Coil Circuit Failure

OBD2 code C1110 flags a problem with the ignition system (ABS power relay coil circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: failed ignition coil or coil pack, worn spark plugs or wrong plug gap, damaged coil wiring or connector.

chassis (brakes/steering/suspension)

Is it safe to drive?

Drive with caution Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm C1110 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many C0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the ignition system for damage, corrosion, chafing or poor contact.
Subsystem check Swap the coil to another cylinder and see if the fault code follows it.
Subsystem check Inspect spark plugs for wear, oil or carbon tracks and check plug gaps.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm C1110 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for C1110 (parts and labor, USD, independent shop rates): Replace spark plugs: $90–$250; Replace an ignition coil: $150–$380; Repair coil wiring or connector: $80–$250. Overall, fixing C1110 usually costs between $80 and $380. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How do I diagnose C1110 myself?

Start with a scan: confirm C1110, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the ABS power relay coil circuit, and verify the suspect component against live data before buying parts.

Is it safe to drive with C1110?

Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

What does OBD2 code C1110 mean?

Will C1110 clear itself?

Sometimes C1110 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of C1110?

The most common causes are: failed ignition coil or coil pack, worn spark plugs or wrong plug gap, damaged coil wiring or connector.

When your vehicle's computer detects a problem with the anti-lock braking system's power relay coil circuit, it stores OBD2 trouble code C1110. This is a chassis-category code, which means it lives in the network that monitors your brakes, steering, and suspension rather than the engine management system. The ABS module continuously watches the relay that supplies voltage to the pump motor and valves. When the coil circuit inside that relay fails to behave within its specified electrical range across multiple drive cycles, the module logs C1110 and illuminates the ABS warning light on the dashboard.

Code C1110 is set after the module performs a self-check and finds the relay coil readings outside acceptable parameters. The fault is verified over more than one drive cycle to prevent false triggers from temporary voltage fluctuations. When the code sets, the module saves freeze frame data — a snapshot showing engine speed, vehicle speed, engine load, and coolant temperature at the exact moment the fault was detected. That snapshot is the most useful piece of information you have, because it tells you under what conditions the problem occurs and guides every diagnostic step that follows.

The symptoms tied to C1110 are noticeable in everyday driving and should not be ignored.

Symptoms of C1110

ABS warning light stays illuminated after startup
Anti-lock brake function becomes unavailable during hard braking
Brake pedal may feel different or pulse unusually during ABS activation
Occasional triggering of the brake warning light alongside the ABS light
Reduced overall braking confidence on slippery or wet road surfaces
Standard (non-ABS) braking remains functional in most cases
Vehicle may display stability control warnings if the system shares circuits with the ABS relay

These symptoms point directly to a loss of power delivery to the ABS pump or valves rather than a mechanical brake failure. The car can still stop using conventional brakes, but the anti-lock and often the traction control functions are disabled.

Common causes of C1110

The root cause of C1110 usually falls into one of three areas: the relay itself, the wiring feeding it, or the control signal from the ECU. The most frequent culprits are listed first.

Failed ABS power relay — the most common cause; the coil inside the relay burns out or loses its ground reference
Corrosion or moisture intrusion at the relay connector — causes intermittent or high-resistance connections
Blown fuse in the ABS power circuit — sometimes overlooked, always worth checking early
Damaged wiring harness between the relay and the ABS module — chafing, rodents, or road debris can expose or sever wires
Faulty ECU output that controls the relay coil — less common but possible, especially after battery or electrical work
Poor ground connection at the ABS module — causes the relay control circuit to read out of range

How to diagnose C1110

Before buying any parts, confirm the code and trace the actual fault through a logical sequence.

Connect an OBD2 scanner to the OBD2 port, retrieve code C1110, and record all freeze frame data and any pending or related codes. Freeze frame data tells you exactly what the engine was doing when the fault was detected.
Check all fuses related to the ABS circuit — a single blown fuse can set C1110 and is the cheapest possible fix. Consult your owner's manual or the fuse box cover diagram for the correct amperage and location.
Visually inspect the ABS power relay and its connector. Look for bent pins, corrosion, greenish oxidation, or a relay that feels loose in its socket. If the relay clicks when the ignition is turned on, it is at least partially working.
Test the relay coil for resistance using a multimeter. Most ABS relay coils read between 40 and 100 ohms. An open circuit or a reading outside the manufacturer's specification means the relay is failed.
Inspect the wiring between the relay and the ABS module for damage, rubbing against chassis components, or connector looseness. Wiggle the harness while monitoring the multimeter to catch intermittent opens.
Clear the code, complete a full drive cycle that reproduces the freeze frame conditions (same speed, load, and temperature), and verify that C1110 does not return. If it returns, you have confirmed the fault is still present.

Repair options and costs

Repairs for C1110 range from a simple fuse replacement to wiring harness repairs or full relay replacement. Prices below reflect parts and labor at an independent shop in USD.

Replace ABS power relay — $120–$300. The relay itself is relatively inexpensive (often $30–$80 for the part), but labor involves removing trim or wheel well panels depending on the vehicle layout.
Repair or replace damaged wiring harness — $150–$400. If the harness has been cut, chafed, or chewed through, repair time varies widely based on accessibility. Splicing and sealing the wires is cheaper than replacing an entire harness.
Replace blown fuse — $0–$30. If a fuse is the cause, the repair cost is essentially nothing for the fuse itself. Labor may be charged at a minimum shop fee for the diagnosis.

A professional diagnosis before purchasing parts is strongly recommended. Shops typically charge $75–$150 for diagnostic labor, which often includes the code retrieval and initial inspection. That fee is credited toward any repair work performed at the same shop.

Can you drive with C1110?

Yes — but with caution. C1110 disables the anti-lock braking system and often the traction control system as well. Your standard brakes will continue to work, but you lose the ability to prevent wheel lockup during emergency braking or on low-traction surfaces. Avoid aggressive braking maneuvers until the code is resolved. If the brake warning light also activates or the pedal feels spongy, stop driving immediately and have the vehicle towed. Never ignore a flashing ABS light combined with a stability control warning — that combination can indicate a more serious electrical fault.