NOTE:

• If the misfiring is frequent enough to trigger detection of increased emissions during two consecutive driving cycles, the MIL will come on, and DTC P0300 (and some combination of P0301 through P0304) will be stored.
• If the misfiring is frequent enough to damage the catalyst, the MIL will blink whenever the misfiring occurs, and DTC P0300 (and some combination of P0301 through P0304) will be stored. When the misfiring stops, the MIL will remain on.

1. Troubleshoot the following DTCs first if any of them were stored along with the random misfire DTC(s):

   P0107, P0108: Manifold Absolute Pressure (MAP) sensor

   P0131, P0132: Primary Heated Oxygen Sensor

   P0171, P0172: Fuel system

   P0335, P0336: Crankshaft Position (CKP) sensor

   P0401, P1491, P1498: Exhaust Gas Recirculation (EGR) system*

   P0505: Idle control system

   P1259: VTEC system*

   P1361, P1362: Top Dead Centre (TDC) sensor

   P1519: Idle Air Control (IAC) valve

   *: D16W7, D16V1 engines

2. Test-drive the vehicle to verify the symptom.
3. Find the symptom in the chart below, and do the related procedures in the order listed until you find the cause.

   Symptom	Procedure(s)	Also check for:
   Random misfire only at low RPM and under load	Check fuel pressure (see page 11-431).	Low compression. Low quality fuel.
   Random misfire only during acceleration	Check fuel pressure (see page 11-431).	Malfunction in the VTEC system (D16W7, D16V1 engine) (see page 6-9).
   Random misfire at high RPM, under load, or under random conditions	Check fuel pressure (see page 11-431).	Correct valve clearance (see page 6-14).