P0155 on Toyota Prius
Factory diagnostic protocol and troubleshooting wire for fault code P0155 specifically for the Toyota Prius (2020–2026, 2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP)).
1. Symptoms of P0155 on Toyota Prius
When the Engine Control Module (ECM/PCM) on your Toyota Prius (2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP)) logs fault code P0155, drivers commonly observe:
2. Most Likely Causes on Toyota Prius
Historical warranty claims and technical repair bulletins for Toyota Prius point to the following failure distribution:
3. Step-by-Step DIY Repair Guide for Toyota Prius
Inspect the O2 HTR fuse in the engine fuse box with a test light or multimeter. on the Toyota Prius equipped with 2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP).
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 Toyota Prius equipped with 2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP).
Remove faulty sensor and install a new OEM oxygen sensor with built-in heater. on the Toyota Prius equipped with 2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP).
Clear DTCs and allow engine to cool down, then restart to confirm P0155 does not return. on the Toyota Prius equipped with 2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP).
Equipment for Diagnosing Toyota Prius (P0155)
Toyota Prius OEM Replacement Sensor
Direct-fit replacement assembly engineered to OEM tolerances for Toyota Prius.
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.
Other Common Fault Codes on Toyota Prius
Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Toyota Prius:
4. Toyota Prius P0155 FAQs
What causes code P0155 to trigger on a Toyota Prius?
On the Toyota Prius (2.0L 4-Cyl Hybrid (M20A-FXS 196HP) / Prius Prime PHEV (220HP)), 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 Toyota Prius?
On the Toyota Prius, the 16-pin DLC diagnostic connector is located Under driver side dashboard near A-pillar trim. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.
Can I safely drive my Toyota Prius 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.