What Does P1105 Mean?
P1105 indicates the heater circuit for the downstream oxygen sensor on Bank 1 (Sensor 2, post-catalytic converter) has a short to the positive supply. The O2 sensor heater is critical for bringing the sensor to operating temperature quickly for accurate catalyst efficiency monitoring. A shorted heater circuit can blow fuses and prevent proper closed-loop fuel control during warm-up.
Common Causes
35%
O2 sensor heater element internally shorted to power
25%
Wiring harness chafed or melted against exhaust causing short to B+
20%
Corroded O2 sensor connector allowing cross-circuit contact
12%
Damaged wiring from improper previous O2 sensor installation
8%
ECM heater driver circuit failure
Diagnostic Steps
1
Step 1: Check the O2 sensor heater fuse. If blown, there is likely a short in the circuit. Replace the fuse only after identifying and repairing the short.
2
Step 2: Disconnect Bank 1 Sensor 2 O2 sensor connector. Measure resistance across the heater pins (typically 2–30 ohms depending on manufacturer). An extremely low or zero reading confirms an internal short.
3
Step 3: With the sensor disconnected, check the heater control wire for a short to battery voltage using a multimeter. The ECM side should show no voltage with the sensor unplugged and key off.
4
Step 4: Inspect the wiring harness from the O2 sensor connector back toward the ECM, paying special attention to areas near the exhaust manifold and catalytic converter where heat damage is common.
5
Step 5: Replace the Bank 1 Sensor 2 O2 sensor if heater resistance is out of specification. Use an OEM or quality aftermarket sensor with matching connector.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
P1105 indicates the heater circuit for the downstream oxygen sensor on Bank 1 (Sensor 2, post-catalytic converter) has a short to the positive supply. The O2 sensor heater is critical for bringing the sensor to operating temperature quickly for accurate catalyst efficiency monitoring. A shorted heat...
The most common cause of P1105 (O2S Heating Circuit Bank 1 Sensor 2 Short To Positive) is: O2 sensor heater element internally shorted to power
Typical repair costs for P1105 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This fault primarily affects emissions and fuel economy. The vehicle is generally safe to drive, but a shorted heater circuit can blow fuses that may affect other systems sharing the same circuit.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1105 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions / Oxygen Sensor Heating
Difficulty
Type
Manufacturer
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