The biggest fear is that the O2 sensor is frozen to the pipe, if this is the case it is a real pain to break it loose. At 236K miles on the O2 sensor (second exhaust system)... going on third, the threads in the bung and the threads on the sensor stripped out. If the head pipe / cat was replaced you will probably be okay. Pre-soaking the O2 sensor with penetrating oil the night before the swap, it might help.

When you install the new sensor, make certain it has anti-seize compound on the threads, if it doesn't, add some you will thank yourself in a few years.

Job takes under an hour including jacking up the car and inserting jack stands (a MUST)assuming the sensor isn't frozen. The connector is easy to get to on the pass side of the firewall.

jorrell
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92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!