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.
P0420 THREE WAY CATALYST FUNCTION - DTC DESCRIPTION
| DTC | M.U.T.-III SE screen terms (Trouble diagnosis content) | DTC detection condition | ||
|---|---|---|---|---|
| P0420 | 00 | TW CATALYST SYS-B1 (Catalyst system efficiency below threshold bank 1) |
Diagnosis condition | - |
| Signal (terminal) | - | |||
| Threshold |
|
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| Diagnosis delay time | - | |||