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eliasbecker7

Oxygen Sensor Heater Failure

I am writing to report an issue with my 2001 Hyundai Terracan, gasoline engine. I am experiencing an oxygen sensor heater failure. The error is stored in the error memory, the check engine light is illuminated, and there is higher fuel consumption. The likely cause is a defective cable or plug connection. The mileage is 23225 km. Has anyone encountered this before?

Summary of the thread

A 2001 Hyundai Terracan experienced an oxygen sensor heater failure, indicated by a check engine light and increased fuel consumption. The likely cause was suspected to be a defective cable or plug connection. After a visual inspection showed no obvious damage, it was suggested to differentiate between the pre-cat and post-cat sensors, with the pre-cat sensor being more likely to affect fuel consumption. A workshop diagnostic confirmed a faulty connection in the pre-cat sensor circuit, which was repaired, resolving the issue.

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4 comment(s)

dirkjung7

Whoa, sounds like a classic O2 sensor heater problem! That malfunction indicator lamp (MIL) staring you down, huh? First things first, have you tried visually inspecting the wiring and connectors going to the O2 sensor? A loose or corroded connection can cause all sorts of havoc. Which O2 sensor is throwing the code – pre-cat or post-cat?

eliasbecker7 (community.author)

Thank you for your reply. I have visually inspected the wiring and connectors, but found no obvious signs of damage or corrosion. Regarding your question, could you clarify how to differentiate between the pre-cat and post-cat sensor? I am not entirely sure which one is the source of the error.

dirkjung7

Alright, if a visual check didn't turn up anything, it's time to get a little more hands-on. Pre-cat (upstream) is before the catalytic converter, closer to the engine; post-cat (downstream) is after the cat. The pre-cat sensor is what the ECU uses to adjust the fuel mixture so that's usually the one that causes increased fuel consumption. If you can't tell, it's probably best to take it to a workshop and have them do a proper sensor testing.

eliasbecker7 (community.author)

I appreciate the detailed explanation and advice. I followed your suggestion and took the Terracan to a workshop. The diagnostic confirmed a faulty connection in the pre-cat sensor circuit. The repair cost 95€. The issue is now resolved. Thank you again for your assistance.

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HYUNDAI

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TERRACAN