DTC Detection Logic
The ECM monitors the switching frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2.
A three way catalyst (manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.
When the frequency ratio of air fuel ratio (A/F) sensor 1 and heated oxygen sensor 2 approaches a specified limit value, the three way catalyst (manifold) malfunction is diagnosed.
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DTC |
CONSULT screen terms (Trouble diagnosis content) |
DTC detection condition |
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P0420 |
TW CATALYST SYS-B1 (Catalyst System Efficiency Below Threshold Bank 1) |
1 |
Diagnosis condition |
- |
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Signal (terminal) |
- |
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Threshold |
Three way catalyst (manifold) does not operate properly. |
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Diagnosis delay time |
- |
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2 |
Diagnosis condition |
- |
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Signal (terminal) |
- |
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Threshold |
Three way catalyst (manifold) does not have enough oxygen storage capacity. |
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Diagnosis delay time |
- |
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