Misfire Rate Catalyst Damage Fault - Bank 1
Your engine is misfiring so badly that the ECU thinks your catalytic converter is being damaged by unburned fuel. Think of it like a fuel injector spraying fuel into cylinders that aren't firing properly, overwhelming your converter's ability to clean the exhaust.
The ECU monitors misfire events using crankshaft position sensor data and compares firing consistency across cylinders on Bank 1. When misfire rate exceeds a threshold (typically 1-2% over 1000 revolutions), the ECU calculates potential catalyst damage risk based on unburned fuel loading.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Misfire Rate Bank 1 | <1% misfires per 1000 revolutions | >1.5% misfires indicating catalyst damage risk |
| Ignition Timing Variance | ±2° variance between cylinders | >5° variance indicating combustion instability |
Code P1336 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1336 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.