[MPoldschool]

Rebuilding the 4.0 in my 2000 TJ, was told I needed to replace all three oxygen sensors. Around $68 a piece, don't mind spending this much if I have to but does all three really need to be replaced or was he a good salesman?

[GOLENJEEPTJ]

Not unless there bad?

[GOLENJEEPTJ]

And which 3 was he speaking of?You should have 2 upstream and 2 downstream.

[retroflow]

Originally Posted by GOLENJEEPTJ

And which 3 was he speaking of?You should have 2 upstream and 2 downstream.

Not necessarily. You have the joy of owning a California Emissions equipped Jeep, which has 4 O2 sensors. Those with Jeeps shipped to other states seem to have just the basic single upstream and downstream fitted exhaust.

As for three sensors...that I'm not 100% on - it's possible. Supposedly, there's a 3rd O2 sensor directly in the Intake Manifold. That could be a typo that's been repeated. I'd have to look into it.

[GOLENJEEPTJ]

Originally Posted by retroflow

Not necessarily. You have the joy of owning a California Emissions equipped Jeep, which has 4 O2 sensors. Those with Jeeps shipped to other states seem to have just the basic single upstream and downstream fitted exhaust.

As for three sensors...that I'm not 100% on - it's possible. Supposedly, there's a 3rd O2 sensor directly in the Intake Manifold. That could be a typo that's been repeated. I'd have to look into it.

There is no 02 sensor in intake.You could be right on the emissions in that year, but I think now it's a Federal Emissions law on the newer vehicles anyway that they all complyI also thought 2000 and up had the 2 piece exhaust manifolds unlike your 97 which call for an 02 sensor on each bank up and below?.The nice thing about California though is we only have a smog check every other year.We don't have the vehicle inspections like so many other eastern states.

[Knuckelhead]

Originally Posted by GOLENJEEPTJ

There is no 02 sensor in intake.You could be right on the emissions in that year, but I think now it's a Federal Emissions law on the newer vehicles anyway that they all complyI also thought 2000 and up had the 2 piece exhaust manifolds unlike your 97 which call for an 02 sensor on each bank up and below?.The nice thing about California though is we only have a smog check every other year.We don't have the vehicle inspections like so many other eastern states.

My 2000 Sport has the 2 part cast exhaust manifold with no mini cats, the only O2 sensors are 1 before the cat next to the TC and one after. This Jeep was originally sold in Colorado, March 2000 build date...
Edit; and no testing here...

[retroflow]

Originally Posted by GOLENJEEPTJ

The nice thing about California though is we only have a smog check every other year.We don't have the vehicle inspections like so many other eastern states.

Depends on the State. PA testing is annual and a royal PIA because there's no regulated flat-rate there. It can be $45 (rare), it could be $59.99 or as much as $74.99-$100..whatever you agree to pay. You really have to shop around.

Now, in CT - Emissions Testing is done every 2 years, like CA. Once a vehicle is over 12 years old, it no longer needs to be Safety Inspected, just Emissions. And the flat-fee is currently only $20 for the test. And unlike in PA, we only have one sticker, not two stickers taking up limited windshield space.