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p2270
Moderate
Mercedes-Benz · Sedans
O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2
Quick Answer
Error code P2270 on your Mercedes-Benz Sedans means: O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
W177W206W214V297A220 2024A220 4MATIC 2024AMG A35 4MATIC 2024AMG C43 4MATIC 2024AMG C63 S 2024AMG E53 4MATIC+ 2024AMG E63 S 2024AMG EQS 53 2024AMG S63 E 2024C300 2024C300 4MATIC 2024E350 4MATIC 2024E450 4MATIC 2024EQS 450+ 2024EQS 580 4MATIC 2024Maybach S580 2024S500 4MATIC 2024S580 4MATIC 2024W223
Likely Causes
  1. Failed downstream oxygen sensor on Bank 1
  2. Exhaust leak near the downstream O2 sensor
  3. Wiring damage or short in the O2 sensor circuit
  4. Contaminated O2 sensor from coolant or oil leaks
How to Fix It
1
Monitor downstream O2 sensor voltage using a scan tool to verify stuck lean reading
2
Inspect O2 sensor wiring and connector for damage or corrosion
3
Check for exhaust leaks between the catalytic converter and the O2 sensor
4
Test O2 sensor heater circuit for proper resistance
5
Replace the downstream O2 sensor if signal is confirmed biased or unresponsive
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Downstream O2 sensor (Bank 1 Sensor 2)
O2 sensor socket wrench
Anti-seize compound
Exhaust gasket
Related Error Codes
P0171P0174P0300P0410P0420
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