Honda 2004 Odyssey Service Manual page 436

DTC P0139: Secondary HO2S (Sensor 2)
Circuit Slow Response
1. Reset the PCM (see page 11-4).
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. Check the secondary HO2S (Sensor 2) output
voltage at 3,000 rpm with the scan tool or the HDS.
Does the voltage stay within 0.3 0.8 V f or
2 minutes?
YES Replace the secondary HO2S (Sensor 2).
NO Intermittent failure, system is OK at this time.
Check for poor connections or loose terminals at
the secondary HO2S (Sensor 2) and the PCM.
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