Multiple Trouble Codes 1997 Toyota Camry

My 1997 camry always ran like a top even though it has over 200 000 miles on it. One day it started missing and hesitating. I put a code reader on it and I got several different codes too numerous to mention.
Could a vacuum leak cause multiple trouble codes? I was thinking about purchasing a smog machine from Walmart and hooking to a vacuum line. Any ideas would be appreciated.

It would help if you posted the codes .

What kind of codes did you get?

P0300 . . . ?!

P0171 . . . ?

A vacuum leak due to a flat gasket could result in misfiring with a cold engine, and it might smooth out substantially as the engine warms up and the gasket partially seals

Yes, but it would be most noticeable at idle.

You’re thinking of purchasing a smog machine at Walmart? Do you mean a fog machine? So you can do what mechanics call a “smoke test”? I’m not sure that idea will work or not. And you definitely don’t want to be blowing something inside of the engine that might damage the internals or the gaskets. A careful inspection of all the vacuum hoses is where to start, followed by testing each vacuum controlled gadget using a hand held vacuum pump to see if they hold vacuum or not. “Mighty Vac” is probably the most widely-sold hand held vacuum pump.

Common causes for a sudden appearance of missing and hesitating:

  • Deferred maintenance. make sure the spark plugs, distributor cap, ignition rotor, spark plug wires, fuel filter, engine air filter are all in good shape.
  • Vacuum leak, especially a split diaphragm at the brake power booster
  • Intake air path leak, check the entire length of the intake air path for split rubber
  • Fuel pressure problem. Check the fuel pressure regulator.
  • Clogged exhaust system or exhaust leak
  • EGR and PCV system problems
  • Evap system problems

From the mileage, symptoms, codes, and other info you did/didn’t give. My advise is replace everything between the bumper covers.

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The codes are as follows;
P0300, P0302 P0303, P0304, P0403, P0402, P0441, P0441 and P0401. I had a check engine light on for years indicating by code the EGR valve was defective. However the car always ran top notch.

Not cost effective to replace everything between the bumpers. That is called the ‘Shotgun Approach’.

This vehicle is not known for too many failures to be honest. What you have described sounds like the one very common failure mode these engines see (I’m assuming its the 4cyl) ?

This failure involves the EGR valve and its control circuit. You need to verify the integrity of your EGR valve first…and from what it sounds like…it is working …just not being controlled correctly. The control comes from the VSV… Variable Switching Valve. It is one of the most common “failures” these vehicles see. You have all the symptoms and codes to go along with this theory.

I just repaird my Aunts 98’ Camry that had the exact same codes and symptoms. What occurs here is that the VSV goes out to lunch…and instead of modulating the vacuum that reaches and controls the EGR…it simply routes full vacuum to the EGR…making it go wide open… When that occurs you get the codes listed along with all those misfires as well…

Look up VSV failure on the net to back up my theory…there are many pages devoted to this failure as it is quite common…and just one thing these vehicles are well known for.

Also… The repair is to buy a GENUINE Toyota VSV… do not buy a cheap aftermarket component as they are typically junk. The solution is a genuine Toy…VSV


This car has adjustable valves . . . the kind that require you to swap out shims of the appropriate thickness

Tight valve lash . . . which you will never hear . . . can lower compression to the point that you can have misfires

If I were you, the first thing I would do is perform a compression test on all cylinders

Please post the results

If all is good there, check and adjust valve lash

Based on the codes you posted, it doesn’t sound like a vacuum leak is the cause of the problems

Usually when I see misfires caused by vacuum leaks, there’s also an accompanying P0171 lean code

However . . . it’s possible there is a vacuum leak large enough to be causing misfires with a cold engine, yet the fuel trims are just below the threshold to generate P0171. Doubtful, in my opinion

As for George’s advice . . . he’s right in principle

That said, I’ve seen guys blow cigarette smoke to locate leaks . . . and it worked


You are not incorrect in any way shape or form @db4690. However the manifestation of symptoms for out of spec valves will happen slowly over time… like one cylinder…then another…then more time…another and it also wont include the P0441 or 401 codes. Those codes and this vehicles known symptoms of VSV failure mode point heavily to the VSV…

The only item that will cause this slew of codes and multiple misfires rapidly…is when the EGR gets hung open during the VSV failure. I literally just buttoned up the 3rd repair of VSV failure in the same number of this vehicle model. Apparently this is how long those VSV’s last…they seem to be failing all over the place now it seems.

P.S… I bet a Camry of this age could use a good valve clearance check and adjustment however…they dont stay adjusted indefinitely…so again…no incorrect suggestions thus far.

Otherwise I might have forgotten about it.

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Yeah, I know valve lash has nothing to do with those other codes

But I think the main thing . . . due to the engine’s age and mileage . . . is to first make sure the engine is mechanically sound

There have been quite a few older vehicles at work that seemed to have relatively minor problems. A little digging revealed that the engines weren’t healthy enough to justify any heroic efforts on our part

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The EGR code(s) you’ve had for several years indicated the EGR wasn’t opening when it should, or not as much as it should. It’s supposed to open during accelerations or higher speed driving situations. There’s two purposes for this, one to reduce emissions, and the other is to prevent the engine’s valves from being overheated and damaged. So the first test is if any of the valves are now damaged, starting w/an engine compression test. This scenerio would be more likely if your driving has a lot of heavy accelerations and long periods of high speed. Put-putting around town, this idea, not so much.

If the compression tests ok, by ignoring the EGR codes, it could have clogged up the EGR passageways; eventually that caused the EGR to stick in a slightly open position. If so that would explain the misfire codes.

You also have codes for the evap purge function. If that problem is ignored it can clog the charcoal canister, dissovled the charcoal, which gets spewed into the injectors, and eventually may clog one or more of them. That would be an alternative explanation for the misfires.

Honda _Blackbird thanks for your input. I am leaning towards a possible cleaning of the EGR valve and replacing the VSV. A visual inspection of vacuum lines and using a hand held vacuum pump also.