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P0402 P0xxx · パワートレーン (P) 重大度中
Exhaust Gas Recirculation Flow Excessive Detected
Too much exhaust gas is entering the intake. The EGR valve is stuck open or the flow signal is over-reading, starving the mixture of oxygen.
重大度の目安： 中 — 走行性または排出ガスに影響。今週中に点検を予約してください
確認できる症状
- Rough idle or stalling
- Lack of power
- Black smoke on diesels
- Hard starting when hot
主な原因
可能性の高い順に並んでいます。上から順に確認してください。
- 1 EGR valve stuck open from carbon
- 2 Faulty EGR position sensor
- 3 Short in the signal circuit
- 4 Incorrect valve fitted after a repair
点検・修理の手順
費用が安く侵襲の小さい項目から — これらのコードの大半は部品の問題ではありません。
- ✓ Watch EGR actual vs commanded position at idle — a valve that should be closed but is not confirms the fault.
- ✓ Remove and inspect the valve for carbon holding it open.
- ✓ Check the position sensor signal sweeps smoothly across its range.
- ✓ Blank the passage briefly with a test plate to confirm the symptom disappears.
修理の選択肢
- Clean or replace the EGR valve
- Clean the EGR passages in the manifold
- Repair the position sensor wiring
P0402 — よくあるご質問
Can I blank off the EGR? +
For off-road or test purposes only. On road vehicles it is illegal in most markets and will fail inspection.
Why does it stall at idle? +
Exhaust gas displaces oxygen in the intake; at idle the engine cannot tolerate the dilution.