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P0155BMWBMW M5 HubAll BMW P0155Medium Severity

P0155 on BMW M5

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

Factory diagnostic protocol and troubleshooting wire for fault code P0155 specifically for the BMW M5 (2020–2026, 4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque)).

Verified OEM Telemetry & Field Repair Tree
BMW M52020–2026
BMW M5
Sedan4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
M5 SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Drivable (Short Trip)
Medium urgency level
Est. Repair Cost
$120 - $350 (DIY: $45 - $120)
Parts & Labor DIY
Check P0155 On Another BMW Model:
Diagnose P0155 on Specific M5 Model Year:

1. Symptoms of P0155 on BMW M5

When the Engine Control Module (ECM/PCM) on your BMW M5 (4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque)) logs fault code P0155, drivers commonly observe:

Check Engine Light on immediately after cold start on BMW M5 (4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque))
Slightly increased cold-start emissions on BMW M5 (4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque))
No major driving performance issues once engine reaches full operating temperature on BMW M5 (4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque))
BMW M5 OBD-II Port Location
The 16-pin diagnostic connector is located Driver lower footwell assembly. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on BMW M5

Historical warranty claims and technical repair bulletins for BMW M5 point to the following failure distribution:

55%
Burnt-out heating element inside the Bank 2 Sensor 1 O2 sensor (BMW OEM Part)
25%
Blown O2 heater fuse in under-hood fuse block (BMW OEM Part)
12%
Corroded or broken heater power/ground wiring (BMW OEM Part)
8%
Faulty heater driver circuit in the PCM (BMW OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for BMW M5.

3. Step-by-Step DIY Repair Guide for BMW M5

01
Check O2 Heater Fuse

Inspect the O2 HTR fuse in the engine fuse box with a test light or multimeter. on the BMW M5 equipped with 4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque).

Required Tool: Fuse Puller, Test Light
02
Test Heater Resistance on Bank 2 Sensor 1

Unplug the sensor connector and measure resistance between the two heater pins. An open circuit (infinite ohms / OL) confirms a dead internal heater. on the BMW M5 equipped with 4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque).

Required Tool: Digital Multimeter
03
Replace Bank 2 Upstream O2 Sensor

Remove faulty sensor and install a new OEM oxygen sensor with built-in heater. on the BMW M5 equipped with 4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque).

Required Tool: 22mm O2 Sensor Socket, Ratchet
04
Clear Codes and Perform Cold Start Verification

Clear DTCs and allow engine to cool down, then restart to confirm P0155 does not return. on the BMW M5 equipped with 4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque).

Required Tool: OBD-II Scanner
Recommended Parts & Testing Tools

Equipment for Diagnosing BMW M5 (P0155)

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Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

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Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

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Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

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Other Common Fault Codes on BMW M5

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the BMW M5:

4. BMW M5 P0155 FAQs

What causes code P0155 to trigger on a BMW M5?

On the BMW M5 (4.4L Twin-Turbo V8 M HYBRID (717HP / 738 lb-ft torque)), P0155 is most frequently caused by Burnt-out heating element inside the Bank 2 Sensor 1 O2 sensor or Blown O2 heater fuse in under-hood fuse block.

Where is the OBD-II port located on my BMW M5?

On the BMW M5, the 16-pin DLC diagnostic connector is located Driver lower footwell assembly. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my BMW M5 with code P0155?

Yes. The sensor will take longer to warm up, causing brief open-loop fuel delay on cold starts. Given that P0155 carries a Medium severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.