A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- The O2 sensor heater has burned out
- O2 sensor heater fuse
- O2 sensor wiring or connector
What you can do yourself
- Check the O2 sensor heater fuse (O2 HTR, HTR, O2S).
- Measure the heater resistance at the sensor connector: a good one reads a few ohms; an open circuit means the sensor needs replacing.
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
Find the part on Kaspi ShopBefore buying, check the part number or match the part by VIN in the Kaspi “Garage”.
Bank 1 is the side of the engine with cylinder 1. An inline engine only has bank 1.
OA case from Oleg’s practice
- Lexus RX350 2008 Check Engine, Traction and ABS are on. The engine has P0037 — B1S2 oxygen sensor heater circuit; the ABS module has no codes: Traction is on because of the engine code. We recommended checking the heater circuit and the sensor. How it went ↗
The explanation comes from the error code reference in the AvtoElektrik PRO app.