P0155
Low SeverityO2 Sensor Heater Circuit (Bank 2, Sensor 1)
Emissions System
What Does P0155 Mean?
Heater failure in the upstream O2 sensor on bank 2.
Common Fix
Replace O2 sensor
Estimated Cost (DIY)
$30 - $100
Symptoms
- β οΈCheck engine light
- β οΈSlightly worse fuel economy cold
- β οΈFailed emissions
Common Causes
Failed heater elementlikely
Blown fusepossible
Wiring issuepossible
How to Diagnose P0155
- 1Check O2 heater fuse
- 2Measure heater resistance
- 3Inspect wiring
- 4Replace sensor
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Frequently Asked Questions
- Is the bank 2 O2 sensor different from bank 1?
- Often yes β bank 1 and bank 2 upstream sensors may have different part numbers due to wire length or connector style.
- Can I use universal O2 sensors?
- Yes, but you must splice the wires correctly. Direct-fit sensors are easier and more reliable.
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