Catalytic Converter System; Dtc Troubleshooting - Honda 2004 Odyssey Service Manual

Catalytic Converter System

DTC Troubleshooting

DTC P0420: Catalytic System Efficiency
Below Threshold
NOTE:
• If some of the DTCs listed below are stored at the
same time as DTC P0420, troubleshoot those DTCs
first, then recheck for DTC P0420.
• Information marked with an asterisk ( ) applies
to '02-04 models.
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater
1. Reset the PCM (see page 11-4), then do steps 2
through 5 to reset the readiness code.
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in Park or neutral) until the radiator fan
comes on.
3. Drive for about 10 minutes, without stopping, on a
highway or freeway. Your speed can vary.
4. With the transmission in D4 (D5) position, drive at
a steady speed between 50 62 mph (80 100 km/
h) for 30 seconds.
5. Repeat step 4 three times. Between each repetition,
close the throttle completely for 1 2 seconds. If
the engine is stopped during this part of the
procedure, go to step 3 and do the procedure again.
6. Check for a temporary DTC with the scan tool or the
HDS.
Does the scan tool indicate T emporary DT C
P0420?
YES Check the TWC. If necessary, replace the
TWC.
NO Check for readiness code completion. If the
readiness code is complete, it was an intermittent
failure, system is OK at this time. If the readiness is
incomplete, repeat steps 2 through 5.
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