Mercedes-Benz Electrical / Sensors Fault Codes — Causes, Symptoms & Repair

Browse 19 electrical / sensors fault codes relevant to Mercedes-Benz vehicles. A fault code identifies the system reporting an out-of-range condition; accurate repair starts with a full diagnostic scan and live-data checks, not a parts guess.

Common Mercedes-Benz Electrical / Sensors Fault Codes

• P2BA9 — Mercedes NOx Limit Exceeded — Adblue
• P229F — Mercedes NOx Sensor B Circuit Low
• P207F — Mercedes Reductant Quality (AdBlue) Performance
• P0606 — ECM/PCM Processor Internal Fault
• P0641 — Sensor Reference Voltage A Circuit
• P2096 — Post-Catalyst Fuel Trim System Too Lean
• P2097 — Post-Catalyst Fuel Trim Rich
• P0601 — Internal Control Module Memory Check Sum Error
• P0602 — Control Module Programming Error
• P0603 — Internal Control Module Keep Alive Memory Error
• P0604 — Internal Control Module RAM Error
• P0607 — Control Module Performance
• B1317 — Battery Voltage High
• B1318 — Battery Voltage Low
• B1342 — ECU Defective
• B1600 — Ignition Key Not Detected (PATS/Immobiliser)
• P0A00 — Drive Motor A Performance
• P0A0F — Engine Failed to Start (Hybrid)
• P0AA6 — Hybrid Battery Voltage System Isolation Fault

What to Do When a Warning Light Appears

• Record the warning message and any change in how the car drives.
• Avoid long or high-load driving if the warning is flashing, the car is overheating, or it has entered limp mode.
• Book a diagnostic scan so the stored code, live data and root cause can be checked before parts are replaced.