Mercedes P0171 P0174 System Too Lean — M271 M272
Mercedes-Benz
C-Class
2004
M271/M272
⚡ Quick Summary
Severity Level
Medium
Safe to Drive?
🚫 Do NOT Drive
Safety Impact
Direct safety risk — affects safe operation of the vehicle
Urgency Level
🟡 Monitor Closely
P0171/P0174 lean codes on Mercedes M271/M272 engines indicate MAF sensor contamination, vacuum leaks or failing secondary air pump. Clean MAF sensor first (£10 spray). Smoke test for vacuum leaks. If codes persist, check secondary air injection system integrity.
Onarım / Çözüm
No confirmed fixes yet. Share yours below.
⚠️ Yanlış Teşhis mi?
No commonly reported misdiagnoses for this fault yet. If you have replaced a part that did not fix this Mercedes-Benz C-Class 2004 problem, submit a wrong diagnosis report — it helps other drivers avoid the same costly mistake.
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