Parts
$30–80
P0161 — O2 Sensor Heater Circuit Malfunction — Bank 2, Sensor 2
SAFEIs it safe to drive? Safe to drive — downstream sensor heater failure is an emissions monitor concern only and will not affect engine operation.
What P0161 means
The heater element in the downstream O2 sensor on Bank 2 has failed or its circuit is open or shorted. The PCM detected that current draw through the heater circuit is out of range.
Most likely causes (in order)
- Failed O2 sensor heater element ($30–80)
- Blown heater fuse (check before buying a sensor — costs nothing)
- Open or shorted heater wiring
- Corroded or loose sensor connector
Symptoms you might notice
- Check engine light on
- Emissions test failure
- No other symptoms for most drivers
What to check first
Pull the heater fuse for the O2 sensor circuit (check your fuse diagram) and see if it's blown — if so, replace it and check for a shorted wire before assuming the sensor failed. Measure resistance across the heater terminals at the sensor directly: good sensors read 4–20 ohms, a dead heater reads open.
Repair cost & difficulty
Labor
0.3–0.7 hr
Difficulty
DIY-friendly