P0042: O2 Sensor Heater Control Circuit — Bank 1 Sensor 3
What to do
No driveability impact. Will block emissions readiness until repaired.
What this code means
A heater circuit fault on a third oxygen sensor in the bank 1 exhaust stream. Three sensors per bank appear on vehicles with more than one catalytic converter in series, where the extra sensor grades the second converter. It sits furthest from the engine and closest to road spray, which makes corrosion the leading suspect.
Likely causes
Start here
- Corroded or loose connector · easy
- Failed oxygen sensor heater element · easy
- Road damage to underfloor wiring · moderate
Less common
- Open circuit in heater wiring · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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