I have a 97 TJ, 2.5l that the check engine light came on. Trouble code showed lean & rich state - replace the O2 sensor with a bosch. Light stayed off for 3 days and came back on. I can reset it, but it comes back. I have gotten a new gas cap, new plugs wires and still no help. Gas mileage has gone from roughly 16 mpg to 9 mpg. Any ideas from anyone???
Both codes indicate it's a problem with the O2's heater circuit. Check the wiring to the sensor. It runs close to the exhaust pipe, it can melt through to it, grounding the heater wire to the sensor. It's the harness side back from the pigtail on the new sensor.
And - note the article also suggests using one from the dealer since aftermarket sensors are often ”one size fits all.”
I've found quite a few times that using one from a parts house gives trouble - especially if its Bosch.
I'm not sure if Chrysler uses the same supplier for the Wrangler O2 sensors...but NGK was the supplier of O2 sensors for my old 98 Dakota. And buying straight from NGK was much cheaper than buying O2 sensors from the dealer.
I'll 2nd the fact that certain aftermarket sensors don't function identically to the original sensors... TPS sensors are another good example of sensors you should purchase from the dealer.
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