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Check Engine Light on 2000 Jeep Wrangler

Hello! Here is my situation and its history:

I have a 2000 Jeep Wrangler, manual transmission, 6-cylinder. I accidentally let the battery die in September. I got a jump, and it was fine until we got a cold snap. (We live in NJ.) On the first cold day (October), the battery was dead again. The battery is about 4 years old. I got it jumped, and it was fine, but the CE light came on. I have been dealing with the CE light and generally lousy engine performance ever since. (The car is lurching and hiccupping.) I have had it to the shop four times since the initial dead battery in September.

I bring it to the shop, they hook it up to the computer, and each time it indicates a sensor problem. They have replaced the 02 sensor, the TPS sensor, cleaned the throttle body, replaced several spark plugs, and swapped out the clockspring. It has been to the shop four times in the past 5 weeks. I even switched mechanics after the first one said he was going to replace the 02 sensor and I looked at my records and pointed out that he had already done that back in June. (At that point, they said “Oh”" and tried replacing the TPS sensor.) The 2nd mechanic also got the TPS sensor code and I told him that the previous mechanic had already replaced that one, as well. He went to a discussion website for mechanics and discovered a “design flaw” that a majority of mechanics said could be rectified by replacing the clockspring. So he tried that. Every time one of these guys does something, the CE light goes off and they test-drive it and it seems fine. Then I come to pick it up, after hours, hours later, when the car has completely cooled off, and the CE light is back on. Yesterday (Thanksgiving morning) I picked it up and the CE light was on but at least it was running better. Then I drove it 90 miles and it was hiccupping badly by the end of the trip. Also, I filled up my gas tank at the beginning of the trip, and the tank is now between 1/2 and 3/4 full. Horrible mileage. My husband made the same trip in a different car, also a Jeep, and also filled up at the beginning, and his tank is more than 3/4 full.

Would love to know if anyone has had a similar problem … I know I can take it to Auto Zone and get the code, but I’m not hopeful that the code will say anything other than what it has already said, i.e. O2 or TPS sensor.


Here’s a thought

It seems probable that none of these mechanics have properly verified their repairs

After clearing a code, all the monitors reset to zero. After that, they’re supposed to drive the car in the appropriate manner, so that all of the monitors run to completion. I’ll wager they aren’t patient enough to do that.

“the car is lurching and hiccupping”

Has anybody measured fuel pressure?

Is the check engine light flashing?

Has anybody checked compression?

Has anybody hooked up a vacuum gauge?

If I’m not mistaken, your Jeep actually has 2 front oxygen sensors, because you have 2 exhaust manifolds, even though you have a straight 6. Bank 1 is cylinders 1-3, Bank 2 is cylinders 4-6

Are you absolutely sure that each time the oxygen sensor code came up, it was for the same sensor?

Have you been using high quality parts?

BTW . . . since the battery is 4 years old, I would seriously consider replacing it. The battery is the foundation for your car’s electrical system, and a marginal one can play havoc with all sorts of things.

And after getting that battery replaced, have somebody test the charging system.

Thank you!

All good idea’s. What was the original incident that let the 4 year old battery run dead?

I’m curious if the same code keeps popping up. @DMNJ, do you know what the code history is? I’m also wondering if the bad battery and constant jumping may have damaged the PCM. Typically, these modules are very hardy and can handle some decent abuse, but, as rare as it is, they can fail. Jump starting can send voltage spikes through the electrical system that has been known to damage modules on a rare occasion.

Arcane, The original incident was that I left the interior light on and then got on a plane. Didn’t come back for a couple days.

As for BustedKnuckles, I do not know the code history, but the 2nd mechanic I brought it to asked the same question. When he hooked it up to the PC, the code referred to a TPS sensor (again). Finally, I brought it to the dreaded dealership. (I know.) This particular dealership is where my husband bought his brand-new Jeep 2 years ago and my husband swears by them. At that point, I thought it was a great idea 'cause I was beginning to realize that I needed a Jeep Whisperer and a dealership might actually have one. I told the Service Manager the entire history and to make a long story short, they discovered that it was the Throttle Position Sensor CONNECTOR. So they replaced that. I picked the car up today. It is running the way it’s supposed to and the CE light is off. Also, it’s very cold out (snowing) and still the CE light is not on, which is good. Previously, it seemed to go on and stay on whenever the engine (or the temperature outside) was cold. So, hopefully, that is the end of the story!