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P0131 P0xxx · 动力总成（P） 中严重度
O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
The upstream oxygen sensor output stays near zero volts — the ECU reads permanent lean. Left alone this drives fuel trims rich and can destroy the catalyst.
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
- Rich running
- High fuel consumption
- Sulphur smell
- Black exhaust soot
常见原因
按可能性从高到低排列——从最上面开始查。
- 1 Signal wire shorted to earth
- 2 Failed sensor
- 3 Exhaust leak before the sensor letting in fresh air
- 4 Water in the connector
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。
- ✓ Watch the sensor voltage: a healthy upstream sensor crosses 0.45 V roughly once per second.
- ✓ Inspect the exhaust manifold and downpipe for leaks ahead of the sensor.
- ✓ Check the connector for corrosion or moisture.
- ✓ Force rich and lean with a propane enrichment or a vacuum leak and confirm the sensor reacts.
维修方案
- Replace the oxygen sensor
- Repair the exhaust leak
- Repair the signal wiring
P0131 —— 常见问题
Is it the sensor or the wiring? +
Watch live data while wiggling the harness. If voltage jumps, it is wiring; if it stays flat, suspect the sensor.
Can an exhaust leak really cause it? +
Yes — fresh air at the sensor mimics a lean mixture, and the ECU compensates by adding fuel.