B1355 — Ignition Run Circuit Failure

B1355 — Ignition Run Circuit Failure. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: damaged coil wiring or connector, faulty ignition control circuit in the ECM, failed ignition coil or coil pack.

body electrical

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 B1355 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 B0xxx 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 B1355 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1355 (parts and labor, USD, independent shop rates): Repair coil wiring or connector: $80–$250; Replace an ignition coil: $150–$380; Replace spark plugs: $90–$250. Overall, fixing B1355 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

What does OBD2 code B1355 mean?

How do I diagnose B1355 myself?

Start with a scan: confirm B1355, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the ignition run circuit, and verify the suspect component against live data before buying parts.

What is the most common cause of B1355?

The most common causes are: damaged coil wiring or connector, faulty ignition control circuit in the ECM, failed ignition coil or coil pack.

What are the symptoms of B1355?

Drivers most often notice: hard starting, especially in damp weather, increased fuel consumption, Check Engine Light on, misfires under load or at idle.

Is it safe to drive with B1355?

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.

When your scan tool displays OBD2 code B1355, the vehicle's control unit is reporting that the ignition run circuit has failed to operate as expected. This fault belongs to the body electrical classification within the OBD2 system, meaning the problem lives in the circuitry that controls how long the ignition stays powered during engine operation. Unlike a simple sensor reading glitch, this code requires the module to detect the fault condition repeatedly under specific driving situations before it triggers the Check Engine Light.

The ignition run circuit performs a straightforward but critical function: it keeps the ignition coil or coil pack energized while the engine is running. When this circuit opens, shorts, or otherwise fails to maintain proper operation, the engine management system loses confidence in the ignition event. The ECU stores B1355 only after confirming the condition meets its internal failure criteria, and it captures freeze frame data showing engine load, RPM, coolant temperature, and vehicle speed at the exact moment the fault occurred. That snapshot is your best starting point for recreating the problem under controlled testing conditions.

Several components share responsibility for the ignition run circuit's reliable operation. The ignition coil or coil pack transforms battery voltage into the high-energy spark needed at each cylinder. The engine control module (ECM) manages the circuit by switching the coil ground on and off at precisely timed intervals. Wiring, connectors, and the spark plugs themselves complete the path from electrical source to combustion chamber. When any link in this chain breaks down, B1355 is the result.

Common symptoms of B1355

Engine cranks slowly or fails to start, particularly when moisture is present in the engine bay
Noticeable increase in fuel consumption during daily driving
Check Engine Light illuminated on the dashboard
Cylinder misfires that may occur at idle or under acceleration
Reduced engine power and uneven throttle response
Rough running behavior that feels like the engine is jerking or stumbling

What causes B1355?

Ignition coil or coil pack failure, the most frequent culprit in this circuit
Internal fault within the ECM's ignition control circuitry
Spark plugs that are worn, oil-fouled, or incorrectly gapped
Moisture intrusion or oil contamination in the spark plug tube wells
Damaged wiring harness or loose/corrosion-affected connectors in the ignition circuit
Poor electrical grounds causing intermittent operation

How to diagnose B1355

Connect an OBD2 scanner and verify B1355 is stored in the control module memory. Record the freeze frame data before clearing anything — those recorded parameters show exactly what the engine was doing when the fault triggered.
Check for any additional diagnostic trouble codes that accompanied B1355. Related codes often point toward the root cause rather than the symptom. Review any manufacturer technical service bulletins that apply to your specific make and model, as some B1355 occurrences have known factory fixes or ECM programming updates.
Perform a hands-on inspection of the ignition system wiring and connectors. Look for wire chafing near heat sources, corrosion at electrical contacts, broken insulation, and any signs of moisture entry. Wiggle connectors while monitoring scanner data to reveal intermittent faults.
Test the ignition coil output with a multimeter or oscilloscope if equipment allows. Alternatively, swap the suspect coil with a known-good coil from another cylinder and observe whether the fault code transfers to the different cylinder.
Remove and inspect the spark plugs. Check electrode wear, gap spacing against factory specifications, and any signs of oil fouling, carbon buildup, or damage from detonation. Replace plugs that show contamination or exceed service intervals.
Clear B1355 after repairs and complete a drive cycle that reproduces the conditions from the freeze frame data. The code must stay cleared through normal operation for the repair to be confirmed.

How to fix B1355

Address the most accessible and affordable components before committing to expensive replacements:

Wiring repair or connector replacement: $80–$250
Ignition coil or coil pack replacement: $150–$380
Spark plug replacement: $90–$250

How much does it cost to fix B1355?

Total repair cost varies based on which part actually failed and your vehicle's accessibility. Parts and labor at independent shop rates typically break down as follows: wiring repairs range from $80 to $250 depending on extent, ignition coil replacement runs $150 to $380 for most vehicles, and spark plug service including labor costs $90 to $250. Most B1355 repairs fall somewhere between $80 and $380 when labor is factored in. The most effective money-saving strategy is proper diagnosis before purchasing parts — the ignition coil represents the highest single cost, yet it is rarely the cause when simpler explanations exist.

Can you drive with B1355?

This fault warrants caution. Misfires caused by ignition circuit failures allow unburned fuel to enter the exhaust stream, and that raw fuel rapidly overheats the catalytic converter. Continued driving risks costly exhaust system damage beyond the original fault. If the Check Engine Light flashes instead of staying solid, reduce speed immediately and reach a repair facility — flashing indicates an active misfire that demands prompt attention.