B1355

Ignition Run Circuit Failure

Body Ignition System Ignition Power Supply 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

Your vehicle's ignition system isn't receiving proper electrical power during the run phase, similar to a light switch that won't stay in the 'on' position. This prevents the engine from running or causes it to stall unexpectedly.

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Symptoms You May Notice

3 known symptoms for this code
Engine cranks but won't start or start then immediately stalls
Instrument cluster lights flicker or dim during starting
No power to fuel pump or ignition coils during engine run
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors voltage supply on the ignition run circuit during engine operation, expecting stable 12V+ power to fuel and ignition systems. When voltage drops below threshold or signal is lost, the ECU detects a circuit failure and sets the code.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Ignition Run Voltage 11.5V - 14.5V during engine run Below 10.5V or open circuit detected
Voltage Stability Steady supply with minimal fluctuation Voltage dropout or intermittent signal loss
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Battery terminals and connectors
Clean corrosion from battery posts and ensure all ignition-related connectors are tight and free of oxidation.
2
Ignition switch
Test continuity through the ignition switch in the run position; replace if contacts are worn or stuck.
3
Main fuses and relay (ignition/run circuit)
Inspect and test fuse links and ignition relays for continuity; replace blown fuses or faulty relays.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1355 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code B1355

What happens after you fix the fault

Once the fault is repaired, B1355 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.