Service Fault Code - Smog Fail Question

I live in CA where my 2002 Saturn passed a smog test in March of this year. I put less than 100 miles on it between then and November, when I wanted to sell it. I smogged it again at the request of a potential buyer and it failed due to a service fault code. The code was a manufacturer specific P040 - EGR “A” Control Circuit Range/Performance. It’s probably related to it needing an oil change but can’t be sure without having someone look closer at it. The car otherwise runs great; no functional or operational issues to speak of. I have a very, very limited amount of money to spend on this. I was selling it because I need money so this is obviously not what I wanted to hear.

My question is this: The check engine light occasionally comes on but goes away within a day or sometimes within minutes. When I got the smog test the check engine light was on, which was a big mistake on my part. I’m thinking that it would have passed had the check engine light not been on at the time since code may not have been “firing”. I’m thinking of not even taking it to a mechanic and just going right back to the smog shop when the light is not on and see if it passes. I spoke with a mechanic over the phone at a different auto/shop shop who thinks it could pass and I should give it a shot. He was most worried about the light coming back on during the test, but it doesn’t usually fluctuate that quickly. I only have one free re-test though so I wanted to get some other opinions. Is anyone familiar with how these service fault codes work that can give me a good guess of whether or not the code would come up again if I re-tested it at a time when the check engine light was not on?

I could be wrong, but I think your code is a PO400…not PO40.

This PO400 would indicate that the EGR valve is not operating properly. The EGR solenoid could be bad or the EGR passage could be plugged with soot and carbon.



The code is almost certainly NOT due to an overdue oil change . . . don’t know where you got that idea

If the engine is running smoothly at ALL times . . . and this is an important detail . . . your EGR valve may have failed, or your EGR passages may be plugged up with carbon.

I suggest you pay to get this properly diagnosed and repaired

I don’t know exactly what kind of EGR system you have, because you didn’t tell us what kind of 2002 Saturn you have

If you clear the code, the light will almost certainly come back, because your engine control module detected a failure. Most likely not a random failure which won’t reoccur

There are several criteria for passing a smog test . . . plug-in in your case, actually

check engine light not on with the engine idling

no fault code which requests the check engine light to be on, regardless of whether the check engine light even works . . . in other words, if you are a smarty-pants kind of guy and somehow disable the check engine light, that plan won’t get you through the smog

the check engine light has to actually work. It needs to come on with the ignition in the on position, and it needs to extinguish with the engine idling

you’re allowed to have exactly 1 incomplete readiness monitor

That incomplete monitor can NOT be the catalyst monitor. In other words, if all are incomplete, except cat, you will fail. On the other hand, if everything is complete except for evap, for example, you’re okay

There’s also some visual inspections, but I’m not going into those, because that’s not the reason your car failed.

A bit of advice . . . if you clear the codes and do NOT pay to fix your problem, at least verify that the car is ready to be smogged before heading over there. Any competent mechanic with a scan tool will know how to check. And if they don’t know how to do that, they’re apparently not as competent as they claim to be

If you somehow manage to get it through the smog without spending any money on repairs, don’t tell that previous would-be buyer that you fixed it. That would be untruthful. The only truthful thing would be to say that you cleared the code, tried to resmog it, and were successful. But the light will probably come back for the same egr problem, and you should tell ANY prospective buyer that

There are ways to game the system, so to speak. In other words, there are ways to show up with 1 incomplete non-cat monitor, pass the smog, and the light will come on the next day. But I’m not going to explain any more. If you’re going that route . . . and I advise against . . . you’re going to have to pay somebody to set that up

Sorry if these are not the answers you were seeking

DB, I did not tinker with the check engine light or the codes in any way, it just goes on and off by itself. And I’m not saying I’m not concerned with the actual issue that might be present, I’m just primarily concerned with it being able to pass a smog. I can’t even park it without risking a ticket until I can get the smog passed.

I’m being as open as I can be with any potential buyer so they will know this code came up, but at the current moment I am only concerned with passing smog and simply want to know: if the check engine light was on when it failed, will it pass if I go back at a time when the check engine light has naturally (aka all on its own with no influence from me) turned off. I’m not looking for ways to game the system, just wondering if it will pass on it’s own if I take it back when the light is off. Apologies if I’m wrong, but I don’t think you answered that.

You can decide what to do without help. If you tell people you had a problem after it is fixed, you might lose the sale. If it’s fixed then it’s not a problem.


Unfortunately it seems like this is devolving into a discussion on ethics. I was not looking for any advice on the ethics of selling a car that may have a problem with it.

I was simply seeking a better understanding of check engine light codes as they relate to failing a smog test. Thank you to those who answered the question that was asked.

Which Saturn do you have? Certain models have a history with this code so whether it is a SL1, SL2 or LS 200 or LS300 or Vue, it is important. It is also important to give us the exact code. It will be a P followed by 4 numbers.

FYI, the SL1 has a history of the EGR valve sticking slightly open so you get the code for failing to close. It is pretty easy to replace, but the port between the valve and exhaust manifold usually has to be sprayed out with gumout. You can clean the valve if you do it yourself. It can be a long and tedious job, not something you want to pay a mechanic to do.

One reason nobody is answering your question is because nobody knows the answer . It might pass when the light is out & it might not .

If you do decide to pursue a repair, and it IS the EGR valve or solenoid/relay, know that the EGR valve can probably just be cleaned out (they pass exhaust gasses, and they occasionally carbon up), and if it needs replacement it’s a $100+/- part and not a really expensive part… and replacement can be done under the hood without disassembling half the car. It’s a basic simple repair.

I understand your frustration OP, the Calif emissions-testing folks have the system set up almost like they don’t want you to pass the test. Since you presumably had the first test done before your registration expired, in my way of thinking it should be perfectly fine for you to continue to drive the car and park the car while you sort the issue out. You have to be able to drive to find the information you need, to get repair parts, take the car to a shop, and take the car back for the second test. But the DMV doesn’t see it that way. They act like they don’t want you to sort the issue out. Been there, done that. I expect it is possible to get a registration extension allowing you to drive the car to the second test if you jump through enough hoops first. And pay a fine or fee. But unlikely if it is for anything other than going to the test site.

As to your original question, yes, it’s entirely possible your car could pass emissions if you could get it there when the check engine light was out and it stayed out for the entire test. Whether it would pass or not – even if the light remains off – depends on so many factors though that about the only way to find out is to try it. If it doesn’t pass, you can post the test results here and we might be able to offer up some suggestions on what to do next.

If you Google Calif Emissions Testing, you’ll see some informative links about how to increase the chances of passing.

One thing is almost certain, it won’t pass if the CEL is on.