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need help figuring out what the problem is 2000 Deville

10004 Views 29 Replies 3 Participants Last post by  Ranger
My Deville just recently went over 100,000 miles and now the "service engine soon" light comes on. Not only that, but the car started like stalling anytime I accelerate from a complete stop. Then the "service engine light" starts blinking. ( Keep in mind I'm not mashing it). I took it to the shop and got the following codes:
Po141-o2 sensor bank 1
Po154-o2 sensor bank 2
po155-heated o2 sensor bank 2
po3000-random misfire
po507-Idle speed high

I got the spark plug replaced, but I didn't get the car scanned again yet. Do the o2 sensors need to be replaced? Or is something causing them to get a bad reading? Where are the fuses for the o2 sensors located? Is all of this related?
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Sounds like you may have CCCCC (Classic case of constipated catalytic converter). A bad cat won't exhaust sufficiently and becomes more obvious at higher throttle settings, ie may idle ok but may load up when you give it gas. I know the PCM compares the downstream O2 sensor to the up streams but don't know what code it would throw. Have you used any kind of solvent around the throttle body? If it contained silicone it will ruin your O2 sensors. You may also need to clean your throttle body using O2 sensor safe throttle body cleaner.

These are thoughts I would have but you may want to post more complete descriptions on the DTCs (codes), hopefully Ranger or Sub will respond, they have forgotten more than I will ever know.
Thx for the quik response. They put some type fuel system cleaner in there not sure about the brand or whether it contained silicone or not. I know that it was pretty high stuff at 160 a bottle (dealership). I was told that would remove any water, deposits, ect from my fuel system. Here are more descriptive descriptions of my codes:
"P0141 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 1 Sensor 2"
P0154 - Heated Oxygen Sensor (HO2S) Circuit Insufficient Activity Bank 2 Sensor 1

P0155 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 2 Sensor 1

P0507 - Idle Speed High
PO3000- Random Misfire

Could a clogged catalytic converter cause the o2 sensors to go bad?
Unfortunately I currently do not own a service manual. Initially I received the following codes when I took it to the shop:
"P0141 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 1 Sensor 2"
P0154 - Heated Oxygen Sensor (HO2S) Circuit Insufficient Activity Bank 2 Sensor 1

P0155 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 2 Sensor 1

P0507 - Idle Speed High
PO3000- Random Misfire

After that the following has been done:
Mechanic checked for any air leaks (forgive my description but I'm a noob at the mechanic stuff) by spraying some type of aerosol spray over the engine
Cleaned the fuel system out with some high end cleaner (name unknown)
Changed all the spark plugs
Checked the fuse ( which seems to have a little give (wiggles) when touching compared to the other fuses)

Today I used that sticky on how to get codes and I recieved the following codes:
PO 140 Circuit insufficient activity Bank 1 sensor 2-History

PO 154 Circuit insufficient activity Bank 2 sensor 1-History

P0155 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 2 Sensor 1-Current

P0300- Engine Misfire Detected- History

I cleared the codes out and I'll drive it tomorrow to see what happens.
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Jaison, check f 20 a red fuse in the under hood fuse block as described on previous post, it is Oxygen Sensors. Also, how did it go when you took it for a drive? You have a full set of spare fuses in the fuse block and inside the lid is the map to show where each one is, what size it is, and its purpose.

Let me know how it goes.
I checked the fuse and the band wasn't broken. After driving it for about 15-20 minutes and checking the DTCs afterwards the only one I got was the P0155 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 2 Sensor 1 (current). So this weekend I think I'm going to replace that sensor. While I do have instructions and a black and white picture I'm still not quite sure where the location is. From what I have been reading it is located on the underneath the car on the front passenger side along the exhaust pipe. Is this correct?
Gulp!! I'm going to give it a shot anyways. Since I'm going to the junkyard this weekend I'll just practice on the one they got up there first. Hopefully Sub will chime in by then. I appreciate your help jimsbox especially the pics. I'll post an update this weekend.
Where do you live Jaison, I am in Kansas City.
You were not exaggerating about it being difficult to access.:bonkers: It was a little to difficult to access from the top. So I ended up accessing to it from the bottom. The pigtail on the O2 sensor and it's connection seem to be good. The wires prior to the covering on the O2 sensor also looked good. In fact the wires looked so good not so sure they haven't been replaced before. But there is no way of me knowing though. I also checked the connection to the pcm and that seemed to be good.( Didn't reconnect it though) I'm actually going to replace it tomorrow. I was thinking while changing the o2 sensor may eliminate the po155 code and get rid of the service engine light. Will changing it stop my car from hesitating when accelerating? It seems like there may be two different issues going on here. Or are they related? Would a clogged catalytic converter or bad catalytic converter give me a DTC?
I replaced the o2 sensor today and .......... it seems to have resolved my problem. Caught hell trying to take that thing off though. I let it run for awhile and I didn't get the P0155 - Heated Oxygen Sensor (HO2S) Heater Performance Bank 2 Sensor 1 message so it looks like all is well. I'm going to take it out this weekend for an extended cruise to make sure it doesn't come back. Thanks Jimsbox and Ranger for your help. Helping me resolve this problem was a hell of a introduction to the forum.
I spoke a little too soon. The PO155 message came back.:mad:Help!!!!!!!
Bosch sensor, and the yes connector is on tight. The service engine light doesn't come on until the car pings and hesitates upon acceleration and then the light blinks on and off. According to the manual this a misfire, correct? In one of Jimsbox earlier post on the topic he stated it could be a clogged catalytic converter. Thoughts?
Still haven't made any progress on fixing my issue, but I've been doing alot of reading and getting the opinions of other mechanics that live near me. At this point I'm going to rule out a clogged cat. I think all of my problems are coming from the p0300-Random misfire code. All of the sensor codes have come and gone and I'm convinced I was only getting them because the car misfires. I still get the p0155- Bank 2 sensor 1, but I noticed it only happens when the car misfires. And after a while the service engine light will go off and when I pull codes the o2 sensor codes are gone.

Pep boys and my neighboor both thought that I needed new ignition coils. Well over the weekend I replaced the rear ignition coil and my car is still misfiring. I looked at the front one and it looks like an aftermarket brand (Delphi) and it doesn't look old or worn. (spring is still springy and no carbon tracking). What else could be causing the misfire? Should I check for a vaccum leak again? If so exactly where do I spray the TB/Carb cleaner?
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No, I haven't but I was looking at this post titled "2000+ Northstar Plenum Duct Replacement steps" which showed the steps. Some of the steps I couldn't follow because of my inexperience such as "bleed of pressure from fuel rail pressure relief valve".Also I couldn't find was how to test the Plenum Duct.
I'm going to test it as soon as I get off. If there were a rip in the plenum shouldn't I be getting a lean code like P0171 - Fuel Trim System Lean Bank 1?
Am I supposed to remove anything other than the vanity cover to test it? I sprayed some throttle cleaner under it but I didn't get a reaction. Thing is I'm not able to get my fingers underneath it to open the tear if it is one. What do I do?
The plentum checked out ok. So I took it to the Cadillac dealership and they told me my problem was coming from a loose fuse in put for the oxygen sensor fuse location. Basically he told me that due to the p0155 code that I kept coming and going that the information was recieved by the ecm and the ecm was compensating for the code which some times resulted in a misfire. They also checked the pressure of the block because I was getting a low coolant message combined with misfires so they considered my hg was going bad. But the pressure checked out ok. Thoughts?
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