P0155 on Toyota
O2 Sensor Heater Circuit (Bank 2, Sensor 1)
P0155 on Toyota vehicles indicates o2 sensor heater circuit (bank 2, sensor 1). Au7o has documented this code across 1 Toyota model — most commonly on Sienna. The PCM has tested the heater circuit of the Bank 2, Sensor 1 upstream O2 sensor and detected a malfunction. The heater brings the sensor to operating temperature for closed-loop control. Indicates a heater element or circuit fault. Typical repair costs on Toyota range from $220 to $2,200, depending on the specific model and root cause.
Common Causes of P0155
- •Failed O2 sensor heater element
- •Open or shorted heater wiring
- •Blown heater fuse
- •Corroded connector
- •Poor heater power/ground
P0155 on Toyota by Model
Toyota Sienna(1 issue)
- P0420/P0430 Catalyst Efficiency Codes Traced to Aged Downstream Oxygen Sensors2004-2010
High-mileage XL20 Siennas commonly set P0420 (Bank 1) and sometimes P0430 (Bank 2) for catalyst efficiency below threshold. On this V6 layout Bank 1 is the rear (firewall) bank and Bank 2 the front, and the van carries four sensors: two upstream air/fuel ratio sensors and two downstream heated oxygen sensors. The most frequent real cause is a lazy downstream sensor whose switching has slowed with age, not a dead converter - but shops routinely quote catalytic converter replacement first, which on this van is a four-figure job. Exhaust leaks upstream of the rear sensor and unresolved misfires also set the code.
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View P0155 across all makes →Frequently Asked Questions
What does P0155 mean on Toyota?▼
P0155 stands for "O2 Sensor Heater Circuit (Bank 2, Sensor 1)." The PCM has tested the heater circuit of the Bank 2, Sensor 1 upstream O2 sensor and detected a malfunction. The heater brings the sensor to operating temperature for closed-loop control. Indicates a heater element or circuit fault. On Toyota specifically, this code is documented across 1 model.
What causes P0155 on Toyota vehicles?▼
Common causes on Toyota: Failed O2 sensor heater element, Open or shorted heater wiring, Blown heater fuse, Corroded connector, Poor heater power/ground. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0155 on a Toyota?▼
Repair costs on Toyota range from $220 to $2,200, depending on the specific model and root cause.
Which Toyota models have P0155 documented?▼
Au7o has documented P0155 on 1 Toyota model: Sienna.