jana_jones2
C70 Oxygen Sensor Heater Error
Summary of the thread
A 2007 Volvo C70 displayed a check engine light with an error related to the oxygen sensor heater circuit, leading to increased fuel consumption. The initial suspicion was a faulty oxygen sensor, despite the cable and plug appearing intact. It was suggested to check the resistance of the heater element using a multimeter to confirm the issue. Ultimately, a workshop confirmed the defective oxygen sensor heater, and after replacement, the problem was resolved.
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4 comment(s)
jana_jones2 (community.author)
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?
danielvogel10
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.
jana_jones2 (community.author)
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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VOLVO
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C70
danielvogel10
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.