LeSabre O2 Sensor Swap, Fix High Fuel Usage Fast

Had similar symptoms with a 1999 Buick Park Avenue. The check engine light triggered due to an oxygen sensor malfunction, which was causing incorrect air-fuel ratio readings. The faulty O2 sensor made the engine computer think it needed to add more fuel than necessary. After inspection, found that the rear oxygen sensor wiring had deteriorated, causing intermittent connection issues. The catalytic converter was also partially clogged due to the rich fuel mixture running for an extended period. The repair required: Replacing both upstream and downstream O2 sensors, Repairing damaged wiring harness, Installing new catalytic converter This was a serious issue since prolonged rich running conditions can damage the exhaust system components. The symptoms matched exactly, sluggish performance and increased fuel consumption. Worth checking the entire exhaust system while the O2 sensors are being replaced. At 190k miles, preventive replacement of related components can prevent future issues and additional labor costs. The wiring harness especially needs thorough inspection as it commonly fails around this mileage.

Thanks for the detailed response about the O2 sensor and exhaust system repair. Really helpful since my LeSabre has similar symptoms. Just curious, do you remember roughly what you paid for the complete fix? Also wondering if youve had any fuel efficiency issues since getting it repaired? My automotive sensor readings still show rich conditions and Im concerned about potential catalytic converter damage like you mentioned.

Took my LeSabre to the mechanic last week and got the issue resolved. The main problem was an aged oxygen sensor with a faulty cable connection, which was causing incorrect air-fuel ratio readings. Total repair cost was 95 for fixing the wire connection, much cheaper than expected. Fuel efficiency has notably improved since the fix. The car runs smoother and fuel consumption dropped back to normal levels. The sluggish performance completely disappeared after the automotive sensor repair. A thorough inspection showed the catalytic converter was still in good shape, likely because I addressed the rich fuel mixture issue before it could cause damage. Car maintenance really does pay off when you catch these problems early. The mechanic confirmed the oxygen sensor readings are now optimal, and the check engine light has stayed off. If your readings still show rich conditions, definitely get it checked soon to protect your catalytic converter.

Thanks everyone for the advice. Finally took my LeSabre to the shop last week. The mechanic found both O2 sensors were shot and the wiring was corroded. Total bill came to €480 including parts and labor. They also inspected the catalytic converter but fortunately it was still okay. The car runs way better now. Fuel efficiency improved immediately, I am getting about 4-5 more miles per gallon. The sluggish acceleration is completely gone too. The check engine light cleared up and hasnt come back. Glad I got it fixed before the rich fuel mixture could cause more damage to the exhaust system. The mechanic said waiting longer could have led to catalytic converter failure which would have been much more expensive. Good lesson in staying on top of car maintenance issues when they first appear.