Honda Civic 2002-2003 Service Manual page 278

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DTC P0300: Random Misfire and Any Combination of the Following:
DTC P0301: No.1 Cylinder Misfire
DTC P0302: No.2 Cylinder Misfire
DTC P0303: No.3 Cylinder Misfire
DTC P0304: NO.4 Cylinder Misfire
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, P1128, P1129: Manifold absolute pressure (MAP) sensor
P0171, P0172: Fuel system
P0335, P0336: Crankshaft position (CKP) sensor
P0505: Idle control system
P1149, P1162, P1163, P1164, P1165: Air fuel ratio (NF) sensor
P1259: VTEC system
P1361, P1362: Camshaft position (CMP) sensor B (Top dead center (TDC) sensor)
P1519: Idle air control (lAC) valve
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.
S m tom
Random misfire only
at low RPM and
under load
Procedure(s)
Check fuel pressure (see page 11·145).
Random misfire only Check fuel pressure (see page 11·1451.
during acceleration
Random misfire at Check fuel pressure (see page 11·145).
high RPM, under
load, or under
random conditions
Also check for:
Low compression.
• Low quality fuel.
Malfunction in the
VTEC system (see page
11-123).
Correct engine valve
clearances (see page 6·
9).
11-71