2011 Subaru P0133: What It Means & Is It Safe to Drive?
P0133 on the 2011 Subaru: O2 Sensor Slow Response (Bank 1, Sensor 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
The upstream oxygen sensor on Bank 1 is responding too slowly to changes in exhaust composition. A healthy O2 sensor switches between rich and lean several times per second; a sluggish sensor causes poor fuel control.
Common causes on the 2011 Subaru
- Aging or contaminated upstream oxygen sensor
- Oil or coolant contamination fouling the sensor
- Carbon buildup on the sensor tip
- Weak heater circuit in the sensor
Symptoms
- Check Engine Light
- Slightly decreased fuel economy
- Possible rough idle
- Failed emissions test
Typical fixes
- Replace upstream oxygen sensor
- Check for oil/coolant burning that could foul new sensor
Repair cost range
For a 2011 Subaru, repairs for P0133 typically fall between $100 and $300, depending on the root cause and labor rates in your area.
Known issues on Subaru
Subaru EJ25 P0133 upstream sensor—the Bank 1 sensor wiring routes along the hot front exhaust pipe and heat damage to the harness insulation is a common cause of false slow-response codes. Inspect the wiring before replacing the sensor.
Most commonly affected models