P0155 on Mercedes-Benz: Symptoms, Causes & Fix
Official technical diagnostic wire for fault code P0155 specifically affecting Mercedes-Benz vehicles (C-Class, E-Class, S-Class, GLC, GLE).
Select Your Mercedes-Benz Model for P0155:
1. Common Symptoms on Mercedes-Benz Vehicles
When Mercedes-Benz Engine Control Modules (ECM) trigger fault code P0155, drivers typically report:
2. Root Causes on Mercedes-Benz Engines
Historical diagnostic claims across Mercedes-Benz engines point to the following failure distribution:
3. Step-by-Step Fix Protocol for Mercedes-Benz
Inspect the O2 HTR fuse in the engine fuse box with a test light or multimeter. on Mercedes-Benz engines.
Unplug the sensor connector and measure resistance between the two heater pins. An open circuit (infinite ohms / OL) confirms a dead internal heater. on Mercedes-Benz engines.
Remove faulty sensor and install a new OEM oxygen sensor with built-in heater. on Mercedes-Benz engines.
Clear DTCs and allow engine to cool down, then restart to confirm P0155 does not return. on Mercedes-Benz engines.
Equipment for Diagnosing Mercedes-Benz (P0155)
Mercedes-Benz OEM Replacement Sensor
Direct-fit replacement assembly engineered to OEM tolerances for Mercedes-Benz.
AstroAI Auto-Ranging Digital Multimeter
Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.
BlueDriver Bluetooth Pro OBDII Scan Tool
Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.
4. Mercedes-Benz P0155 Frequently Asked Questions
What does code P0155 mean on a Mercedes-Benz?
On Mercedes-Benz vehicles, P0155 indicates that the Engine Control Module (ECM) detected o2 sensor heater circuit malfunction (bank 2 sensor 1). This typically points to Burnt-out heating element inside the Bank 2 Sensor 1 O2 sensor or Blown O2 heater fuse in under-hood fuse block.
Can I continue driving my Mercedes-Benz with code P0155?
Yes. The sensor will take longer to warm up, causing brief open-loop fuel delay on cold starts. Because this code carries a Medium severity rating on Mercedes-Benz powertrains, we recommend scanning live data values promptly to prevent secondary damage.
How much does it cost to fix code P0155 on a Mercedes-Benz?
Estimated DIY parts cost ranges from $120 - $350 (DIY: $45 - $120), while professional shop repairs at an authorized Mercedes-Benz dealership or independent specialist typically range from $180 to $380 including diagnostic labor.