What Does P1108 Mean?
P1108 indicates the Bank 2 Sensor 1 oxygen sensor heater circuit is producing an output that is too low. The upstream O2 sensor heater on Bank 2 is not generating enough heat to bring the sensor to its optimal operating temperature of approximately 600°F. This results in delayed closed-loop fuel control on Bank 2, increased cold-start emissions, and potentially rich running conditions during warm-up.
Common Causes
35%
O2 sensor heater element degraded with high internal resistance
25%
Poor electrical connection at the Bank 2 Sensor 1 O2 connector
18%
Low voltage supply to heater circuit due to wiring resistance
12%
Blown or weak heater circuit fuse or relay
10%
ECM heater driver circuit providing insufficient ground
Diagnostic Steps
1
Step 1: Measure O2 sensor heater resistance at the Bank 2 Sensor 1 connector (disconnect the sensor first). Typical resistance is 2–30 ohms. Higher readings indicate a degraded heater element.
2
Step 2: Verify battery voltage is present at the heater power wire with the key on. Low voltage here indicates a wiring, fuse, or relay problem.
3
Step 3: Check the heater ground circuit by measuring voltage drop from the heater ground pin to battery negative with the heater commanded on. More than 0.5V indicates excessive ground resistance.
4
Step 4: Inspect the O2 sensor connector and harness for heat damage, corrosion, or broken wires, especially near the exhaust manifold where Bank 2 Sensor 1 is located.
5
Step 5: Replace the Bank 2 Sensor 1 O2 sensor if heater resistance is out of specification. Clear codes and monitor heater current draw to confirm proper operation.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
P1108 indicates the Bank 2 Sensor 1 oxygen sensor heater circuit is producing an output that is too low. The upstream O2 sensor heater on Bank 2 is not generating enough heat to bring the sensor to its optimal operating temperature of approximately 600°F. This results in delayed closed-loop fuel con...
The most common cause of P1108 (O2 Sensor Heating Circ.,Bank2-Sensor1 Output too Low) is: O2 sensor heater element degraded with high internal resistance
Typical repair costs for P1108 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Primarily an emissions concern. The vehicle will run richer during cold starts until the sensor reaches operating temperature naturally, increasing fuel consumption and tailpipe emissions but posing no immediate safety risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1108 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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