matholland

Hey guys. Just picked up my second 99 I have owned. Runs and drives good, but if it sits and idles too long, it starts spuddering until you take off, sputters just a second and is fine the rest of the time. It has 4 codes, 2 current, and 2 pending. Before I buy new ngk sensors, does it sound like my issue?

P0132- O2 sensor circuit high voltage (bank 1 sensor 1)
P0138- O2 sensor circuit high voltage (bank 1 sensor 2)
P0135- O2 sensor heater circuit (bank 1 sensor 1)
P0141- O2 sensor heater circuit (bank 1 sensor 2)

I know the bank 1 sensor 1 is the upstream is before the cat and the bank 1 sensor 2 is after the cat.

Anyone have the part number for the 2 if it sounds like it just needs new o2 sensors?

CCKen

Sounds like the O2S Heaters fuse in the PDC may be blown.

The fuse is a 15 Amp mini fuse in the row closest to the firewall.

matholland

I'll have to look when I get off work. Is there 2 heater fuses or only 1?

2000chersport

One

matholland

Gotcha! Thanks guys! I will look when I get home, and if not I will order 2 new ones. Is the one behind the cat all that helpful? What I mean by that is will the downstream one cause the issues that I am experiencing, or just the upstream one?

matholland

Got home today, fuse was blown. I replaced it and drove it around for a while, and let it idle, and the issue is gone. Thanks for the info guys!

CCKen

I'll have my cookie now thank you. :-)

matholland

Update...fuse blew again....will a bad o2 sensor blow them, or do I have a wiring issue?

2000chersport

Just inspect the wiring real quick. It should be obvious if the wires rubber coating has melted/rubbed away. The wires could be touching each other.

Happened to me. The driveshaft rubbed through the wires on the downstream and kept shorting it out.

And at a different time, the upstream wires had the rubber coating melted away somehow and were shorting out by the plug harness the O2 sensor plugs in to

matholland

The elastic or whatever you call it on the downstream was ate off, the driveshaft was hitting it...But I couldn't find anywhere that the wires were showing. I unplugged that one, and I put a new upsteam in since I had ordered one from amazon, and replaced the fuse. I will see if it still blows the fuse or if it is good.

The exhaust is cut off right after the cat...The guy wheeled it, so my guess is that water got up into there and messed one or both of them up. I will keep ya updated!

matholland

Just am update...Drove it over 100 miles today...check engine light is on since my second one is unplugged but I haven't blown any fuses and it runs much better. Probably going to order the other o2 sensor in a few days as long as it doesn't blow a fuse. The one that got caught in the driveshaft must have had 1 little wire poking out or something that I didn't see would be my guess on the 2nd o2 sensor. Fingers crossed.

extrashaky

Current can arc through insulation in the right circumstances.

On my 2000 there is a little bracket up in the tunnel above the drive shaft that is supposed to hold the wires up away from the drive shaft so that doesn't happen. The connector for the O2 sensor actually snaps into it with one of those plastic snap clips to keep it in place. It's not easy to see unless you slide all the way up under the Jeep. When you install the new sensor, check to see if yours has that bracket, and if so, make sure the wires are routed up there to get them out of the way.

matholland

Gotcha! I will place it up there. The clip was broke off on the old one. So far so good, no blown fuses, and I have drove it over 200 miles since I installed a new one on the downpipe and removed the one after the cat. Doesn't get a rough idle after sitting for a few minutes like it did. Hell, if it wasn't for the check engine light, I wouldn't put a new second one in. I did think about taping up the old wires on the other one and seeing if it blows a fuse. Can these pop fuses if they are going out? If they don't then I will tape it up and zip tie it up there out of the way of the drive shaft. If they do, then I will just replace it.

extrashaky

Go ahead and replace it. Since you've already removed the old one, the most difficult part is already done. While the downstream sensor is less important than upstream, the computer still uses that data. Also, if you're riding around with a CEL, and something else throws a code, you won't know it because you'll think it's just your O2 sensor warning. You're basically defeating your early warning system.

Be sure to use anti-seize compound on the threads, to keep it from locking up in there for the next replacement. If you didn't do that on the upstream sensor, you might want to pull it and put some on there.

matholland

Yeah, I put additional anti-seize on the threads when I installed it. It's not like they were hard to pull out. Hate waisting money if the old one is good. I will tape the old one up on each individual wire, then wrap them all tonight and install it to see if it blow a fuse again. If it does, then I just saved 40 bucks.