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P0430 P0xxx · 动力总成（P） 中严重度
Catalyst System Efficiency Below Threshold (Bank 2)
The bank 2 catalytic converter is no longer storing enough oxygen to smooth the exhaust — the downstream sensor is switching too much like the upstream one.
严重程度说明： 中——已影响行驶或排放，请本周内安排检修
你会注意到的故障现象
- Failed emissions test
- Slight loss of power
- Sulphur smell
- No obvious drivability change in mild cases
常见原因
按可能性从高到低排列——从最上面开始查。
- 1 Ageing or overheated catalyst
- 2 Exhaust leak between the two sensors
- 3 Downstream O2 sensor lazy or biased
- 4 Engine running rich or misfiring for a long period upstream
如何排查
先做花钱最少、侵入最小的检查——大多数这类码不是零件问题。
- ✓ Rule out an exhaust leak first — it is free to check and a common false cause.
- ✓ Compare upstream and downstream sensor waveforms; a healthy downstream signal is nearly flat.
- ✓ Check fuel trims and misfire counters — fix the cause before condemning the catalyst.
- ✓ Measure back-pressure to rule out a physically blocked converter.
维修方案
- Replace the catalytic converter
- Repair the exhaust leak
- Fix the upstream rich/misfire fault first
P0430 —— 常见问题
Is the converter definitely dead? +
Not always. Fixing an exhaust leak or a rich-running fault clears maybe one in four of these codes.
Can I use a universal converter? +
You can, but on OBD-II-monitored vehicles a correctly specified converter avoids comebacks.