P0155
System
Powertrain (Emissions)
Scanner required
Basic OBD2 code reader (engine codes, live data, smog readiness)

O2 Sensor Heater Circuit (Bank 2 Sensor 1)

Understand P0155, common causes, and the right TOPDON scanner to diagnose it.

Heater circuit for bank 2 upstream O2 sensor. Common high-mileage failure on V-engines.

Common symptoms

  • Check engine light
  • I/M readiness monitor not ready

Typical causes

  • Failed O2 sensor
  • Heater fuse
  • Connector corrosion

What scanner do you need?

Basic OBD2 code reader (engine codes, live data, smog readiness)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

Can I diagnose P0155 with a basic code reader?
Yes — P0155 is typically accessible with a basic OBD2 code reader like the TOPDON ArtiDiag201 or TopScan Lite. Live data helps confirm the repair.
Is it safe to drive with P0155?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.