C70 Oxygen Sensor Heater Error

I own a 2007 Volvo C70 with a gasoline engine. Recently, the check engine light came on, and it shows an error about the oxygen sensor heater circuit. Fuel consumption seems higher than usual. I suspect the oxygen sensor, but the cable and plug look fine. Any ideas?

4 comment(s)

Oxygen sensor heater failure is common on these. The heater element inside the sensor often goes bad. Have you checked the resistance of the heater element itself, using a multimeter? If it's open circuit, that confirms it.

I haven't checked the resistance of the heater element directly. Could you tell me where exactly I need to measure and what a normal resistance value would be?

I don't have the exact resistance value, but an open circuit means it's definitely faulty. Probe the two pins on the sensor connector that correspond to the heater element (check the wiring diagram, maybe labeled HE+ and HE-). Given the symptoms, and no obvious wiring issues, get a workshop to confirm it before replacing it.

I took the car to the workshop and they confirmed the defective oxygen sensor heater. The repair, including parts and labor, came to 95€. Now everything is working fine.

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