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Check Engine Light Goes On/Off on Toyota Camry

I have a persistent recurring problem that neither the dealer nor independent repair shops have been able to fix. I have a 1996 Toyota Camry, and the “check engine” light goes on and off for no apparent reason. The repair guys have told me it has “something” to do with the emission control system. I have paid to have the charcoal canister, valves, hoses, gas cap, etc. etc, (pretty much everything but the catalytic converter) replaced, and still the light comes back on. It may have something to do with the “oxygenated” fuels in summer, or that could just be coincidence. After the light comes on, it usually goes off after a period of driving. Sometimes that period is a week, and sometimes it is several months. Then the light stays off for awhile – again sometimes a short time, sometimes several months – before coming back on again. I can’t get my car emissions tested with the light on, and I am tired of wasting money for “repairs” that don’t fix the problem. Has anyone else run into this problem? Any suggestion? Thanks!

When the check engine light goes on diagnostic trouble codes (DTCs) are stored in the computer. You need to find out what these codes are and post them with your question or no one even knows where to start.

If your mechanic has scanned and gotten codes, check your receipts or call and ask. You want to be able to post an actual code (e.g. P0123) not what anyone says about them.

Or many chain auto parts stores (e.g. Advance, Autozone) will read these for free.

Also report any unusual problems with how the car is performing and some basic info about how well you keep up with basic maintenance.

I’d also suggest a new mechanic since this one seems to be throwing parts at things rather than really diagnosing them. There are lots of DTCs and correct ways to test components to isolate problems.

It’s pretty near impossible to diagnose this sort of thing from a distance. My guess would be that it is a Loose Gas Cap" (small pressure leak) problem and that it may or may not be legitimate.

The first thing I’d suggest is buying a cheap code reader. I happened to drop by Autozone today looking for something else and noticed that their cheapest code reader is on sale for $50 this week. With the code scanner, you can tell what code you are getting, and you can clear it. If it is coming up at random, you might very well be able to clear the code and get the car inspected before the code returns.

I think you might be able to clear the code without a scanner by removing and reinserting the (as I recall) EFI fuse in the fusebox in the engine compartment fuse box. The fuse layout is printed on the inside of the fuse box cover. Works on my 1999.

1996 was the first year for mandatory OBD-II diagnostics. A few 1996 and 1997 models from some companies had some troubles with the diagnostics not working right sometimes. I don’t know if Camry was one of them. Might want to check in the appropriate Camry forum at and see what they think.

Thanks for the advice. I had tried to reset the code, but I was pulling a different fuse. The engine light went off, so at least they will run the test now. If I can slip by, great. Otherwise I will follow up with the OBD scanner. The car always passes when they run the test, so I think your suggestion that the diagnostics aren’t working right may be correct. Again thanks.

Get your car emissions tested when the light goes off; then, you’ll have a lot more time to worry about getting the EVAP system fixed.
The DIAGNOSTIC TROUBLE CODES (DTCs) would help us, a whole lot, to diagnose the problem; otherwise, we can’t help you. Bring those codes here, and we’ll see.

At first, I missed it; but, I just saw that you said, “The car always passes when they run the test,…” Is that the State Mandatory Emissions Test? If so, you will have time to find the right repairer, and save money on incorrect troubleshooting (if that’s the correct word.)

Same thing, 1999 Camry.
It was a solenoid valve that allows fuel vapor to flow into the charcoal cansister. I opened up the electrical connector and cleaned the contacts and the problem went away.

I have the same problem with 1999 Camry, goes off and comes back in 3 days… and very irregular. Checked the DTC code at AUTOZONE: P0401.

What should I do.
Thanks a lot for help.