2002 Chrysler Concorde O2 problems (long)

My daughter is driving this car. Started running bad and CEL came on. Over the phone she told me codes were P00135 & P00155. Since I was on my way home from work I met up with her to follow her home so the car was driven about 30 miles after the problem first showed up. When I pulled the car in the shop to change out the O2 sensors, I checked the codes. It was now showing five with P00132, P00135, & P00300 added to the two above.

From the FSM, P0132-O2 SENSOR 1/1 VOLTAGE HIGH, P0152-O2 SENSOR 2/1 VOLTAGE HIGH, P0135-O2 SENSOR 1/1 HEATER PERFORMANCE, P0155-O2 SENSOR 2/1 HEATER PERFORMANCE, & P0300-MULTIPLE CYLINDER MISFIRE. Further checking verified these are the upstream sensors mounted in the exhaust manifolds.

When I replaced them, the CEL light didn’t go out so I checked codes again. P00132 & P00152 remained. I pulled the appropriate fuse to reset and took the car for a short drive, < 5 miles. The CEL light remained off. I drove it to church the next day, about 12 miles each way. It ran OK with the exception of surging at low rpm’s. I picked up a set of plugs while in town that Sunday and put them in that afternoon. It ran good without surging for the test drive after spark plug replacement. CEL remained off.

The next day when my daughter drove it to school the CEL light came back on. Same drive distance as trip to church. The P00132 & P00152 codes are back. I’ve examined wiring and checked resistance in the ground circuit from what I saw in the FSM. The ground all seems to be good, but I couldn’t get steady readings from my meter, or sure about the accuracy. I have a good Fluke meter, but unsure that it is working right.
It runs and idles smoothly, but those codes just won’t go away and come right back when I pull the fuse to reset. Since I don’t have a DRB III , I am at a loss at this point.

Is it time to take it to a professional with the right equipment to get to the bottom of this, or is there something else I can do?

As always, thanks upfront for any tips, ideas, or solutions offered.

edit: correction on codes that remained 132 & 152 not 135 & 155 as stated earlier.

The heater circuit is basic, you need to have a wiring diagram to check the correct terminals. For a quick check, check all the fuses and fuse links then look at the wiring harness for wires that have made contact with the exhaust, or rubbed through. HTH, Steve

Thanks Skeptic. I do have full wiring diagrams in the FSM. That's how I found and checked the ground circuit. The reason I checked the ground circuit is from what I saw in the diagnostic of the FSM. I've also given it a good visual inspection as you noted for wire issues and found nothing.

Is there anyway to attach a pdf? I tried it and it shows attached?? I've extracted two pages from the FSM that contain the diagnostic, but the procedure uses a scanner. Maybe someone can provide some guidance on how to test without a scanner.
Or maybe it just can't be done?

I agree with skeptic as the codes that came back are for the two upstream 02 heaters. Check the wireing as I remember some years the heaters were powered from the ASD relay and some years right from the PCM or an ign 12 volt feed. They should have a fuse for them most likely in the PDC under the hood but you need to follow with wires in the manual to see where the feed comes from. It may also have blown the heater fuse do to a short as I had pinched wires to the 02 heaters do that before and also a bad 02 heater. If you can take a pic of the wires and post it we could help more. Ron

Wow life and work. I've finally gotten back to this. BTW, I fixed the first post were I wrongly listed 135 & 155 as the codes that remained. It is 132 & 152.
Also, I have taken the car to work 5 times now and it runs good except an occasional rough idle.

I've attached pictures of the wiring, but I can find nothing wrong with it. I am also attaching the schematic from the FSM. From what I see the heater circuit is powered directly from the pcm with no fuses. I measure 8.9 volts at the connectors on both upstream sensors on the heater circuits, that stays at 8.9. Grounds back to the body or engine show a about .3 ohms resistance.

Following steps 2 & 3 of the diagnostic I measure just under 2.5 volts. But I must admit I'm at a loss of why check the return voltage if it is a heater circuit issue. Could one or both of the new O2 sensors be bad, or the wrong ones?

The codes reset at about 30 seconds after start. Still baffled.

Where did you measure 2.5 volts ? I ask because some years bias 2.5 volts on the ground side of the sensor signal wire as the sensor instead of reading from 0 to 1 volt reads from 2.5 to 3.5. Ron

383 Man, Thanks. I just went and checked it again to make sure. At the K902 18 BR/DG per the schematic I attached in the last post. Measurement taken at the plug connection to the sensor on the left bank which is the 1/1 sensor.

Hard codes wont leave the computer memory by pulling a fuse.They will stay and sometimes light as soon as power is back sometimes later.They need to be erased with a scanner.Just reading codes tells you where a problem is you need to read live data to be accurate.Rocky

Well if those two codes came back on, it's likely something else; vacuum leak, leaking fuel injector, etc.