這東西不光是震蕩範圍，還有波形。輸出到ECM的信號是另外的。需要在不同的probes之間測量。最好找到本田的維修手冊或者Haynes手冊。需要比較前後sensor 的波形和輸出。
我仔細看了看我的Camry手冊，現學現賣。
O2 sensor 回路故障另外有碼（P130,133,135,136 and 141）。P420 專指催化係統效率未達到要求。如果你僅僅讀到P420而沒有其它碼，好像確實要懷疑催化劑失效。但你的現象僅僅在雨天出現，我覺得還是什麽地方的電路問題。而且你說後麵的sensor波動速度慢，根據下麵的原文，如果催化劑壞了，前後波動速度應該一樣。
另外一個懷疑點是空氣進口A/F sensor。
摘錄原文供你參考。
The ECM compares the waveform of the heated oxygen sensor located before the catalyst with the waveform
of the heated oxygen sensor located behind the catalyst to determine whether or not catalyst performance
has deteriorated.
Air–fuel ratio feedback compensation keeps the waveform of the heated oxygen sensor before the catalyst
repeatedly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor behind the catalyst switches
back and forth between rich and lean much more slowly than the waveform of the heated oxygen sensor
before the catalyst.
But when both waveforms change at a similar rate, it indicates that catalyst performance has deteriorated.
(a) Connect the TOYOTA hand–held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OX1, OX2 and E1 of the ECM connector.
(b) Start engine and warm it up with all accessories switched OFF until water temp. is stable.
(c) Race the engine at 2,500 ~ 3,000 rpm for about 3 min.
(d) After confirming that the waveforms of the heated oxygen sensor (bank 1 sensor 1 (OX1)), oscillate
around 0.5 V during feedback to the ECM, check the waveform of the heated oxygen sensor (bank
1 sensor 2 (OX2)).
If there is a malfunction in the system, the waveform of the
heated oxygen sensor (bank 1 sensor 2 (OX2)) is almost
the same as that of the heated oxygen sensor (bank 1
sensor 1 (OX1)) on the left.
There are some cases where, even though a malfunction
exists, the MIL may either light up or not light up.
我仔細看了看我的Camry手冊，現學現賣。
O2 sensor 回路故障另外有碼（P130,133,135,136 and 141）。P420 專指催化係統效率未達到要求。如果你僅僅讀到P420而沒有其它碼，好像確實要懷疑催化劑失效。但你的現象僅僅在雨天出現，我覺得還是什麽地方的電路問題。而且你說後麵的sensor波動速度慢，根據下麵的原文，如果催化劑壞了，前後波動速度應該一樣。
另外一個懷疑點是空氣進口A/F sensor。
摘錄原文供你參考。
The ECM compares the waveform of the heated oxygen sensor located before the catalyst with the waveform
of the heated oxygen sensor located behind the catalyst to determine whether or not catalyst performance
has deteriorated.
Air–fuel ratio feedback compensation keeps the waveform of the heated oxygen sensor before the catalyst
repeatedly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor behind the catalyst switches
back and forth between rich and lean much more slowly than the waveform of the heated oxygen sensor
before the catalyst.
But when both waveforms change at a similar rate, it indicates that catalyst performance has deteriorated.
(a) Connect the TOYOTA hand–held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OX1, OX2 and E1 of the ECM connector.
(b) Start engine and warm it up with all accessories switched OFF until water temp. is stable.
(c) Race the engine at 2,500 ~ 3,000 rpm for about 3 min.
(d) After confirming that the waveforms of the heated oxygen sensor (bank 1 sensor 1 (OX1)), oscillate
around 0.5 V during feedback to the ECM, check the waveform of the heated oxygen sensor (bank
1 sensor 2 (OX2)).
If there is a malfunction in the system, the waveform of the
heated oxygen sensor (bank 1 sensor 2 (OX2)) is almost
the same as that of the heated oxygen sensor (bank 1
sensor 1 (OX1)) on the left.
There are some cases where, even though a malfunction
exists, the MIL may either light up or not light up.
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