P0142 — O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
Can drive — fix at your convenience.
What P0142 means
This code means the heater circuit inside the downstream oxygen sensor on Bank 1 (Sensor 2) isn't working as expected. The built-in heater normally warms the sensor quickly so it can start reading exhaust accurately, and a fault here is usually caused by a burned-out heater element, a blown fuse, or wiring and connector problems. The most common fix is replacing the oxygen sensor, since the heater is built into it.
Common symptoms
- Check engine light is on
- Slightly reduced fuel economy
- Failed emissions or smog test
- Longer time before emissions monitors complete
- No noticeable change in engine power
Common causes
- Burned-out heater element inside the oxygen sensor
- Blown fuse on the sensor heater circuit
- Damaged or corroded heater wiring
- Loose or faulty electrical connector
- Less commonly, a control relay or computer fault
Typical repair cost
$150 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0142 code?
Usually yes, at least short term. The fault is in the sensor's heater, not the engine itself, so the car should run normally. Still, get it looked at within a week or two and expect a failed emissions test until the heater circuit is repaired.
How much does it cost to fix a P0142 code?
Most repairs fall between $150 and $400. Because the heater is built into the oxygen sensor, the usual fix is a new sensor plus labor. If the real problem is just a blown fuse or a wiring fault, the cost can be lower.
Is a P0142 code serious?
No, it's typically low-severity. Your engine isn't in danger and the car drives normally, but the slow-to-heat sensor affects emissions monitoring and can slightly hurt fuel economy. It's best fixed promptly so emissions readiness completes and the car can pass inspection.
What does the O2 sensor heater do in P0142?
The heater warms the oxygen sensor to operating temperature quickly after a cold start, so it can read exhaust accurately before the engine itself heats it. When that heater circuit fails, the sensor takes too long to work, which is what P0142 flags. Replacing the sensor usually restores fast, reliable readings.