Melissa Long

Dear people of the internet,

If anyone can confirm where the O2 sensor (bank 1, sensor 1) is on a 99 Jeep Grand Cherokee Laredo is that would be very helpful.




What is the sensor that had wires cut?
This it?

jon-d

I am not sure, but the two sensors I have one is located near the header as in your first photo, and the second one is near the cat. I cannot tell where your second photo was taken. if you could take it further out, or multiple photos that might help.

dave1123

Welcome to CF!

If you have CA emissions, there are 4 02 sensors on it. 2 before the cats and 2 after. Bank 1, sensor 1 is the front 3 cylinders and before the cat. The cats are small and are before the collector where the 2 pipes join into 1 large pipe. I'm assuming you have the 4.0 from your photos.

If you only have Federal emissions, there are only 2, one in the header just above the collector and one after the inline cat under the jeep. Again, from your photos, it appears you have Federal emissions, so Bank 1, sensor 1 is the sensor in your first photo. It also looks like someone replaced one of the exhaust manifolds with a CA emissions one and just cut off the wires to the upper one.

I don't know your location, but several states have adopted CA emission standards for vehicles sold in their state. NY is one of them. The exhaust manifolds are cast iron and will crack, so the junkyards are the logical place to find a replacement. The manifolds for the Federal and CA emissions are the same except for that threaded hole for an 02 sensor.

Sorry to be so late in responding, but your photos had me scratching my head for awhile.

jon-d

I guess I have a non-kalifornia model based on your description Dave....

dave1123

Yeah, it gets confusing. My Jeep is a NY one with CA emissions. I actually had to go to the FSM to figure this out for the OP. My inline cat under the jeep doesn't have an 02 sensor at all. Also, the jeep only has to have emissions for whatever state was it's original delivery point AND the regulations in effect at time of delivery.

97grand4.0

Sensor 1 is always closest to the engine. That much I know. I think.

dave1123

That's right. When it comes to Bank, the V8s are Bank 1 is the side with cylinder #1, the 4.0 has a split manifold and Bank 1 is the forward 3 cylinders, again with #1 cylinder. Sensor 1 is always the upstream sensor and 2 is the downstream one.

Melissa Long

You have all been a big help. Glad I found this forum.

dave1123

No worries, that's what we're here for. At least I am! I'm retired and am on the forum at least once a day.