B1359 — Ignition Run/Acc Circuit Failure

How much does it cost to fix B1359?

Replace spark plugs — $90–$250; Repair coil wiring or connector — $80–$250; Replace an ignition coil — $150–$380. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Will B1359 clear itself?

Sometimes B1359 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 B1359?

The most common causes are: damaged coil wiring or connector, failed ignition coil or coil pack, moisture or oil in the spark plug wells.

What does OBD2 code B1359 mean?

OBD2 code B1359 flags a problem with the ignition system (ignition run/acc circuit failure). Short, gentle driving to a shop is usually possible. Common culprits: damaged coil wiring or connector, failed ignition coil or coil pack, moisture or oil in the spark plug wells.

How do I diagnose B1359 myself?

Start with a scan: confirm B1359, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the ignition run/acc circuit, and verify the suspect component against live data before buying parts.

When your vehicle's engine control module detects that the ignition run/acc circuit is not behaving as programmed, it stores trouble code B1359. This code falls under the body electrical category and translates to "Ignition Run/Acc Circuit Failure." The circuit in question handles power delivery to the ignition system during normal engine operation, and when it strays outside acceptable parameters, the PCM logs this fault.

The PCM does not set B1359 after a single bad reading. It requires the abnormal condition to repeat under specific operating conditions before illuminating the check engine light. When the code is stored, the freeze frame data captured at the same moment becomes your most valuable diagnostic tool. This snapshot records engine load, RPM, coolant temperature, and vehicle speed at the exact instant the fault occurred—recreating those conditions during testing gives you the best chance of catching the problem.

Common Symptoms of B1359

• Difficulty starting the engine, especially in damp or humid conditions
• Noticeable loss of engine power and irregular acceleration
• Fuel economy that drops below normal levels
• Cylinder misfires that occur either at idle or under load
• Rough running or hesitation during throttle input
• Check Engine Light remains illuminated
• In some cases, the CEL may flash continuously during active misfiring

What Causes B1359?

• Worn or damaged spark plugs, including incorrect electrode gap settings
• Defective ignition coil or coil pack unable to generate proper secondary voltage
• Damaged wiring, melted insulation, or corroded connectors in the ignition control circuit
• Poor electrical connections at the ignition coil, ECM, or related modules
• Internal ECM failure affecting the ignition control circuit driver
• Aftermarket accessories interfering with factory ignition circuit operation
• Shorted or open circuits in the harness due to age, heat exposure, or physical damage

How to Diagnose B1359

1. Connect an OBD2 scan tool and confirm B1359 is present. Before clearing anything, record all freeze frame data—this tells you the exact engine conditions when the fault triggered.

2. Look for any related diagnostic trouble codes. Addressing secondary codes first often reveals the root cause of B1359. Check manufacturer TSBs for your specific make and model; many ignition-related faults have documented factory fixes or software calibrations available through the manufacturer website or NHTSA database.

3. Perform a hands-on inspection of all wiring and connectors tied to the ignition system. Pull back protective looms, check for cracked insulation, corroded pins, loose terminals, and any signs of water intrusion or heat damage.

4. Test the ignition coil's primary and secondary resistance with a multimeter against factory specifications. Alternatively, swap the suspected coil into a cylinder that is functioning normally and monitor whether the fault migrates with it.

5. Remove and examine the spark plugs. Look for worn electrodes, carbon tracking, oil fouling, or gaps that deviate from the manufacturer's specification.

6. Clear the code and complete a drive cycle that mirrors the conditions captured in the freeze frame data. If B1359 does not return, the repair was successful.

Repair Options and Costs

• Replace spark plugs: $90–$250
• Repair or replace damaged wiring and connectors: $80–$250
• Replace an ignition coil or coil pack: $150–$380

How Much Does It Cost to Fix B1359?

The final invoice depends entirely on which component is actually at fault. Independent shop rates in the United States typically break down as follows: spark plug replacement runs $90–$250, wiring or connector repair costs $80–$250, and an ignition coil replacement lands between $150–$380 for parts and labor combined. Most B1359 repairs fall somewhere in the $80–$380 range. Starting with visual inspection and basic component testing before purchasing expensive parts is the most cost-effective approach—the priciest scenario is rarely where you should begin.

Can You Drive with B1359?

Proceed with caution. Ignition-related faults cause misfires that allow unburned fuel to enter the exhaust stream, and this can overheat and destroy the catalytic converter in a relatively short distance. If your check engine light is flashing rather than solid, do not continue driving—pull over and address the problem before it causes secondary damage.

Related OBD2 codes

• B1300: Power Door Lock Circuit Failure
• B1301: Power Door Lock Circuit Open
• B1302: Accessory Delay Relay Coil Circuit Failure
• B1303: Accessory Delay Relay Coil Circuit Open
• B1304: Accessory Delay Relay Coil Circuit Short To Battery
• B1305: Accessory Delay Relay Coil Circuit Short To Ground