So Service Engine Light came on the other night...

[Joey04GXP]

And I noticed that the gas mileage was severley altered. Had more than 3/4 tank and all of a sudden it read 127 miles til empty. Brought her to Pep boys to have them run a full diagnostic test on it. All codes came back to O2 sensor. Upon further inspection, it seems the Secondary Air pump is INOP and need to be replaced. Dealer only part. Got an appointment at the local Caddy dealer tonight to drop her off. Anyone else ever have this part replaced? Don i need to take a 2nd mortgage out to pay for this? Cause anytime "Dealer" is involved with getting parts and labor you KNOW it's expensive! Lol!

[CMNTMXR57]

It's actually not to overly difficult to replace. It's on the lower front driver's side corner. Depending on your arm size/flexibility, you might be able to get it from above, once you remove the airbox. But it will be easier to get the front of the car in the air, remove the lower air dam/splash shield, and it's right there. Looks like a little pump with two medium sized rubber hoses coming to/from it. You'd probably end up spending more on the labor than the pump itself if you let them do it. This is provided, the troubleshooting has indicated that the pump is truly faulty.

Which gets me to the core of my issue here, you state that it has had poor fuel economy, the resultant cause of which is a faulty O2 sensor, and from that, the seconday A.I.R. pump is faulty. Something isn't connecting in my head. Was there a P0410, P0412, or P0418 code set?

The Secondary A.I.R. System is only commanded on only when the coolant temp is 41* - 176*, and your IAT's (intake air temps) are greater than 41*. The concept of the A.I.R. system (A.I.R. stands for Air Injection Reaction, just coincedently it's acronym is AIR) is that it operates by injecting fresh air into the exhaust stream, which in turn helps light off the catalyst in your converter, getting the converter hot, faster than without it, which in turn, gets the PCM into closed loop operation faster. When the PCM is in closed loop, it is using the O2 sensors (along with everything else, to determine the proper A/F ratio). In Open Loop, the car is actually running richer than it should to compensate until Closed Loop has occured. But regardless of whether the Secondary A.I.R. system working or not, the PCM will eventually go into Closed Loop mode anyway, and your O2's *should* be doing their job of maintaining a stoich level. If not, that's an O2 sensor issue, as the Secondary A.I.R. system would have no impact here, even if it's non-function slowed down the vehicle's ability to get into Closed Loop. After the vehicle is in Closed Loop mode, all the Secondary A.I.R. system is, is dead weight in the car. It isn't used until next start up and the conditions listed above are met (I.E. ECT between 41* - 176*, and IAT's >41*).

About the only thing that I'm thinking that a Pep Boys scan could flag with the Secondary A.I.R. system (outside of the 3 codes I mentioned above) in relation to the O2 sensors, is that if the PCM runs a Closed Loop "test" by monitoring the O2 sensor voltages during normal operation, then commanding the A.I.R. pump on as part of that "test". Once it commands the pump on, it determines any A.I.R. fault based on the change in the O2 sensor voltage. Those voltage's should decrease with the pump on. If so, the A.I.R. system is functioning properly and passes the test. If not, or it's slow to decrease those O2 sensor voltages, it'll fail and trigger a DTC.

But either way, a poor mileage condition to me, is more O2 sensor related. Not a fault of the A.I.R. system. That may just be another problem on top of it.

[GXPete]

Wow. Remember when all there was to an automobile engine was some cylinders, spark plugs, a distributor, an air filter and a carburetor?

[CMNTMXR57]

Kinda a double edged sword though. Since today's cars do everything via PCM control, when something goes wrong, they literally tell you what the problem is. Conversely, when an engine was just some cylinders, spark plugs, distributor, air filter, and carb, you had to know a lot of theory to torubleshoot where a problem lay. With that distributor, You had to know how to manually time them Adjusting for how a degree or two of change affected reliability, efficiency, driveability), removing vacuum advance lines to do that, etc, and then setting dwell to boot. You had to figure out fuel deliery/lack of delivery issues, etc. You also had to adapt them for each season of the year.

Today, I just plug in my Tech 2 and it tells me what's wrong, then from experience of troubleshooting these codes, I go right to the source of the problem. So I see both sides of the fence.

When I get into re-doing my '66 Catalina, It'll be a crash course in all those basic things again since it's been some 15 years since I last timed an engine with a timing light, set dwell, worked on a carburetor (other than small engine carbs), etc.

[GXPete]

Sweet! You have a '66 Catalina? I actually learned to drive in a '75 Catalina. I hate GM for dropping Pontiac.

[CMNTMXR57]

Yes. IT was my first car when I turned 15. But it has been in the family since my great-great grandparents bought it new in 1967.

[GXPete]

Cool. You should have that in your sig. Got any pictures?

[CMNTMXR57]

Yea, I guess I could. It's not driveable or in the best shape right now. It's been really sitting for the past 20 years.

Most pictures I have aren't really of the car, more that it just got in the way.

[GXPete]

Awesome. My brother had either a Catalina or Bonneville during that body style. He's actually here visiting (lives in California) so I think I'll ask him what he had. His was blue as well, but a darker blue than yours. That is going to be nice when you get it fixed up. Storing the ramps on the roof is a sin though. Is that a vinyl top?

And yes, I envy your air jack.

[CMNTMXR57]

No, full steel. No worries on the ramps being up there, the whole car is in rough shape, so they aren't doing much damage. It's sorta actually my workbench right now.

That air jack is virtually useless now. It was great when I had my trucks/SUV's, but on most of today's cars, the Bonneville included, they're too low and don't really have a good lifting point for it. I remedied that though with a Bend-Pak HD9ST 4 post lift in the place where the Catalina is sitting in those pictures.

[harofreak00]

No jibber-jabber in the Mechanical forms, please stay on topic.

8 posts that have absoluetely zero information the original poster.

[GXPete]

My bad. I guess I started the off-topic discussion. But I think CMNTMXR's initial reply was all that was required for the original poster. We were just shooting the breeze while waiting to see if he needed further assistance.

[Joey04GXP]

It's actually not to overly difficult to replace. It's on the lower front driver's side corner. Depending on your arm size/flexibility, you might be able to get it from above, once you remove the airbox. But it will be easier to get the front of the car in the air, remove the lower air dam/splash shield, and it's right there. Looks like a little pump with two medium sized rubber hoses coming to/from it. You'd probably end up spending more on the labor than the pump itself if you let them do it. This is provided, the troubleshooting has indicated that the pump is truly faulty.

Which gets me to the core of my issue here, you state that it has had poor fuel economy, the resultant cause of which is a faulty O2 sensor, and from that, the seconday A.I.R. pump is faulty. Something isn't connecting in my head. Was there a P0410, P0412, or P0418 code set?

The Secondary A.I.R. System is only commanded on only when the coolant temp is 41* - 176*, and your IAT's (intake air temps) are greater than 41*. The concept of the A.I.R. system (A.I.R. stands for Air Injection Reaction, just coincedently it's acronym is AIR) is that it operates by injecting fresh air into the exhaust stream, which in turn helps light off the catalyst in your converter, getting the converter hot, faster than without it, which in turn, gets the PCM into closed loop operation faster. When the PCM is in closed loop, it is using the O2 sensors (along with everything else, to determine the proper A/F ratio). In Open Loop, the car is actually running richer than it should to compensate until Closed Loop has occured. But regardless of whether the Secondary A.I.R. system working or not, the PCM will eventually go into Closed Loop mode anyway, and your O2's *should* be doing their job of maintaining a stoich level. If not, that's an O2 sensor issue, as the Secondary A.I.R. system would have no impact here, even if it's non-function slowed down the vehicle's ability to get into Closed Loop. After the vehicle is in Closed Loop mode, all the Secondary A.I.R. system is, is dead weight in the car. It isn't used until next start up and the conditions listed above are met (I.E. ECT between 41* - 176*, and IAT's >41*).

About the only thing that I'm thinking that a Pep Boys scan could flag with the Secondary A.I.R. system (outside of the 3 codes I mentioned above) in relation to the O2 sensors, is that if the PCM runs a Closed Loop "test" by monitoring the O2 sensor voltages during normal operation, then commanding the A.I.R. pump on as part of that "test". Once it commands the pump on, it determines any A.I.R. fault based on the change in the O2 sensor voltage. Those voltage's should decrease with the pump on. If so, the A.I.R. system is functioning properly and passes the test. If not, or it's slow to decrease those O2 sensor voltages, it'll fail and trigger a DTC.

But either way, a poor mileage condition to me, is more O2 sensor related. Not a fault of the A.I.R. system. That may just be another problem on top of it.

Sorry it took mwe so long to re-post but did you ever nail it right on the head. Seriously, the GM techs explained it to me EXACTLY the way you did! Kudos to you on that! Also had to get a Sylenoid replaced. Will check the paperwork when I get home and post which one it was. Car is running much better now.

[CMNTMXR57]

No problem. Many people (IE Pep Boys) automatically throw the A.I.R. pump in and tell you that that's the cause because that is a big dollar item vs. an HO2S. Or they simply don't know.

But a driving issue with poor economy is something related to an online function (I.E. O2's, MAF, MAP, TPS, tune, filters, etc, etc). The Secondary A.I.R. system is only used to help quicken the time for the PCM to get into Closed Loop operation. It should have no affect on drivability or economy.

[Joey04GXP]

No problem. Many people (IE Pep Boys) automatically throw the A.I.R. pump in and tell you that that's the cause because that is a big dollar item vs. an HO2S. Or they simply don't know.

But a driving issue with poor economy is something related to an online function (I.E. O2's, MAF, MAP, TPS, tune, filters, etc, etc). The Secondary A.I.R. system is only used to help quicken the time for the PCM to get into Closed Loop operation. It should have no affect on drivability or economy.

Now that I'm thinking it over a bit more, I believe the MAF sensor was replaced as well. I'm "discussing" payment solutions with the dealer i bought the car from. I flew down from NYC to Ft. Lauderdale a few weeks ago, signed all the paperwork, and then drove the car over a 1000 miles back home, only stopping for gas/bathroom & some food. I parked the car, went to sleep, then when i started the car the next day the service engine light was on. I just feel that the dealer should help me out with at least 1/2 payment(total price was $785 for the fix). I don't think that I'm being unreasonable. They assured me that they conducted a thorough check of the car and that I would have no problems. We'll See what happens.

[CMNTMXR57]

No problem. Many people (IE Pep Boys) automatically throw the A.I.R. pump in and tell you that that's the cause because that is a big dollar item vs. an HO2S. Or they simply don't know.

But a driving issue with poor economy is something related to an online function (I.E. O2's, MAF, MAP, TPS, tune, filters, etc, etc). The Secondary A.I.R. system is only used to help quicken the time for the PCM to get into Closed Loop operation. It should have no affect on drivability or economy.

Now that I'm thinking it over a bit more, I believe the MAF sensor was replaced as well. I'm "discussing" payment solutions with the dealer i bought the car from. I flew down from NYC to Ft. Lauderdale a few weeks ago, signed all the paperwork, and then drove the car over a 1000 miles back home, only stopping for gas/bathroom & some food. I parked the car, went to sleep, then when i started the car the next day the service engine light was on. I just feel that the dealer should help me out with at least 1/2 payment(total price was $785 for the fix). I don't think that I'm being unreasonable. They assured me that they conducted a thorough check of the car and that I would have no problems. We'll See what happens.

They should have a dealer warranty on the car. At least 30 days or something. Not a dime should come out of your pocket. Especially if it's CPO!

[Joey04GXP]

They should have a dealer warranty on the car. At least 30 days or something. Not a dime should come out of your pocket. Especially if it's CPO![/quote]


That's really how I feel. But they are saying all sales are final. And that GM might pay half of the bill. I will take whatever I can get from them at this point. I'm already out the $ as I paid for repairs. Main thing is the car is fixed! Anyway, here were the things that were replaced:
1:N6608 Emissions System Wiring(Wiring Harness) and/or Connector- item#15319851 Relay
2.J6400 Evaporative Emission Cannister Purge Solenoid Valve Replacement- Item#12581282
3.J5670 Mass Air Flow Sensor Replacement. Item#15904068

Total Price w/Labor= $785.15

[CMNTMXR57]

How many miles are on the car? Sounds like they're going to "Goodwill warranty" some of it thorugh GM. But what are the laws in your state? Any dealer that sells a car usually has at least a 30 day warranty on all cars sold (or something like that). That should cover anything that does go wrong. If it's a CPO vehicle, there should be no questions asked.

That's odd that your purge solenoid and your MAF went. What codes was it getting to trigger those replacements? I'd sorta be skeptical as to why they replaced those without reason.

[Joey04GXP]

How many miles are on the car? Sounds like they're going to "Goodwill warranty" some of it thorugh GM. But what are the laws in your state? Any dealer that sells a car usually has at least a 30 day warranty on all cars sold (or something like that). That should cover anything that does go wrong. If it's a CPO vehicle, there should be no questions asked.

That's odd that your purge solenoid and your MAF went. What codes was it getting to trigger those replacements? I'd sorta be skeptical as to why they replaced those without reason.

Car has just over 33K. I have the list of codes from pep boys but the sheet is kind of faded as their ink in machine was low. I'll check it when i get home. And I left deposit on car via ebay. then flew to Florida to buy it. Not first time i bought from ebay. All other times vehicles were fine. Not sure about FL law regarding car sales. Will check into it though. thanks

[CMNTMXR57]

Well, I was gonna say it Manufacturer warranty was 3yr/36k, so you'd still be in mileage wise, but you're obviously out based on time. Sounds like I said above, because of the mileage, they're squeaking it under what GM calls "goodwill warranty". They "grey" area if you will around the 3/36.

But regardless, I would still think a dealership, even in Florida, as a matter of sales enticement to consumers (and possibly as a law), would warranty anything they sell for a minimum amount of time/mileage too.