PontiacBonnevilleClub.com

Hello all. I just found my first Bonneville. It's a nice car, but I've got a few questions. Alright, so it's a 2004 GXP, 34,500 miles. First little trip was about 100 miles. Well, of course I had to see if it was gonna meet my expectations with the V8. I was a little rough, passing everything in sight. Well, I'm not sure who had it before, but I put premium gas in it. So on the way home after rough housing, I got the SES for the cat converter. At that many miles, is it really possible it needs to be replaced? The only reason I ask is because maybe it sat up, then I put premium and blew some crud out? I dunno, not an expert here. Or could it just be a bad sensor? I hate to go chopping up my exhaust to replace something that doesn't need to be replaced.
Next question, kinda related to the above. Does the car always run warm? It stays at the 200 degree mark, but it's like everything under the hood is that temp. To touch the air filter while running was like touching the radiator hose. The place where I park it, the grass is dying under it because of the heat. Just wondering if this is normal or not? My WS6 never got that hot. Maybe it's the confined space under the hood?
Last one, when I checked the cabin air filter, I opened up the compartment, and the filter was just sitting there. No bracket to hold it. I just grabbed it, took it out, and could see the fan down there. Is that normal as well or am I missing a bracket? I mean, it's just a hole with a filter laying flat in it. Just looked odd to me.
Sorry if I'm asking repeat questions, but I've read through a lot of posts and haven't come across anything yet in reference.
Thanks for your replies!

I can speak to the cat issue. Take it to a GM dealer. There is a recall and they will replace the whole exhaust from the headers back. I had mine done last March. Same question on the cabin filter as well. I think there is a bracket.

there should be a bracket for the Filter

I'm definitely gonna take it in. Thanks for that info! Do you think they'll replace it since its 9 years old?
And I don't even know why that bracket would go missing. That's crazy.

the 01+ cars never came with a Bracket.....yes its crazy. It didnt go missing, you never got one.

you can buy a filter and bracket all in one as a replacement.

the warrenty on the cat is 8 years or 80,000 miles which ever comes first

As for the temperature, the gauge is set to read 200 even all the way up to around 210 - 215 degrees. The Northstar is a hot running engine, I would guess they did it this way so that people don't get alarmed that the temp gauge reads above 200. During the short time I had one I had a scan gauge in it and it always ran higher then 200, but only raised above 200 on the dash when the actual temperature was around 220. Really nothing to worry about, and as far as under hood temps go, with the combination of a massive DOHC V8 engine that runs hot normally being shoehorned into a spot designed for a V6, everything just gets and stays hot.

Question 1: It is probably a catalyst below efficiency code. P0420 or P0410 (I can never remember which is which), for a car that only has 35k on it and is ~9 years old, it sounds like it, and the post-cat O2 sensor (which is usually the actual issue), never gets really hot enough to burn off the soot it gets from running a little rich from short trips as a 35k mileage car suggests. 90% of the time, it is simply that the post-cat O2 sensor either needs a good cleaning and/or replacement.

Question 2: First, your gauge on your dash, isn't certified calibrated and moves degree for degree with what your ECT's are. It's more or less a dummy gauge in that a temp reading of 190* - 210* will set the gauge in roughly a small range of actual movement. Second, in today's emissions laden, CAFE burdened world, ALL engines are run hotter on purpose to help burn off excess hydrocarbons. So yes, they run hot.

Question 3: I see this was answered and I don't recall ever seeing brackets on the later Bonneville's. It's just a drop in.

Thanks for all the replies. That's great info. I called the GM dealer, no recalls on the VIN of my car. So no go there.
I did price the rear O2 sensor, about 50 bucks, so I'll replace that Friday. I'd rather start there. The car runs like a sewing machine. Just odd things on this car that would be abnormal on most others. Thanks again! Relieved my worries for now. Ha!

Oh, and it's the P0420, low efficiency.

Shazam! This code is actually the PCM trying to run an I/M system test (readiness monitor), on the catalyst. Once it fails, it will keep trying to run it until it passes, OR you can manually run it if you have a Tech2 (or other suitable tool), as you need to turn on the cooling fans manually to ensure they don't kick on during the test (as it will change load values and fueling values, which in turn impact the Post-cat O2 readings potentially).

So... try cleaning the one in there now. Pull it out, and anything like an electronics cleaner, brakekleen, etc, will do the trick then drive it, and let it try to run the test on it's own.

Thanks! And thanks for staying in touch with this forum. I've learned a lot from your previous posts. Since I got the car so cheap, I can afford to invest in things like the HID fog lights and the separate transmission cooler, and cold air intake. Now, just keep in mind I'm an old shade tree mechanic, not too familiar with the GM electronics and abbreviations. Your explanation of the self test was a little over my head. Lol. And of course I don't have either scanning tool. So I'm gonna clean first then replace. I work on a cardiac floor, so by the time I'm done mixing meds, reviewing ekgs and all that other crap, my brain is too fried to interpret GM lingo, but I'm trying!

Thanks.

The I/M system in GM speak is the Inspection/Maintenance system, or many times referred to as a "readiness monitor". Cliff Notes: All these systems the PCM of the car supports have to communicate with the main server (the PCM in this case). AS such, the PCM sends tests out to them randomly to see that they're online and active. Stuff like Catalyst test, Heated oxygen sensor tests (HO2S), EGR test, Secondary A.I.R. tests, refrigerant tests (believe it or not), etc. If it (the PCM), sends out a test to one of these systems and it doesn't respond either through loss of communications and/or simple failure (as is the case here), do to not meeting the thresholds of the tests, it sends back a failure to the PCM. The PCM will then continue to run that particular test until a "PASS" is achieved.

Anyway, you can clean/replace the post-cat HO2S, and just drive the car, and after it runs and passes the test on it's own, it will stop running that particular test (it will run it again randomly at some point in time), after 3 consecutive successful tests before turning off the MIL (Malfunction Indicator Light), or your SES/check engine light), on the dash. The code will then move to a historical file where it gets purged after 40 consecutive, successful operating cycles.

Or you can force the PCM to run the same test on your terms as a diagnostic, but as I said, you would need a scan tool.

Well, unscrewed the o2 sensor. Piece of cake and found 2 of the wires naked from rubbing each other. I'm guessing that's a problem. Taped them back up and now gonna see it it resets itself.

Glad to see your O2 issue was an easy fix.

I concur, new cars just plain run hot.

Cabin Filter info: http://www.pontiacbonnevilleclub.com/fo ... 13626.html

Thanks! I'm not sure it's fixed quite yet. The light is still on. One more trip into town tomorrow will tell. Then, I'll buy some cleaner and do it again if it doesn't go out.

Thanks for the air filter info. That application looks way better than a filter just laying in a hole. Lol.

Thanks again everyone!