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Toyota Service
Toyota Service, Toyota Expert
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2005 Toyota Sienna: Van..warning lights..check engine, vsc and TRAC

Resolved Question:

I have a 2005 Toyota Sienna Van. Three warning lights on the dash are on together from time-to-time: check engine, VSC and TRAC OFF. The Toyota Dealer first said I needed two catalytic converters, then one. I spoke with a guy at a national auto parts store and he said he doubts it's the catalytic converter since the lights come-and-go. What should I do?
Submitted: 5 years ago.
Category: Toyota
Expert:  Toyota Service replied 5 years ago.

Toyota Service : Hello. Welcome to Just Answer. Please allow me to assist you. Do you have the results of a recent diagnostic scan available? Thanks


Toyota Service : Then why did the dealer tell you you needed cats?
Toyota Service : What did he base his decision on?

not sure. they checked it out and said so. might have done scans but I don't know exactly what they did.

Toyota Service : Ok.

I keep all the paper work in the glove compartment. I can go check and see if they gave me scan results but I doubt it.

Toyota Service : For some reason, toyota lights up those three lights when there is a problem in the system, all 3 lights is normal, it indicates you have an issue.

does it necessarily mean cats?

Toyota Service : A print out would be great, the DTCs specifically
Toyota Service : Not necessarily

I'll check and be back in a few minutes. Can you hang on?

Toyota Service : Sure

be right back

Toyota Service : Ok. Take your time.

All I found was an invoice that said: "PO430 Tested EEC System. Cat Converters need to be replaced. E." They quote me some outrageous price - more than $2,000 if I remember correctly. I said I couldn't do that, then they started back-peddaling and said something about only needing one and the cost being less than $1,000. Didn't instill a lot of confidence.

Toyota Service : I agree. You don't tell a customer you need a 2 grand worth of cats, then change your tune when the customer balks at the prices.
Toyota Service : There are a few things that can trick the sensors into thinking the cats are compromised.
Toyota Service : When was the last time you had a good tuneup?

It has 145K miles on it and I have taken it in pretty faithfully for 5K mile maintenance until they pulled this stunt. That was probably 10-15K miles ago, so I've done most everything recommened up until that time.

Toyota Service : You using genuine Toyota spark plugs?

I've just been taking it into Valvoline for the 10 minute oil changes the past couple of times.


Since the Toyota dealer did all the work up until recently I assume they are Toyota plugs.

Toyota Service : Ok
Toyota Service : Since the lights are intermittent, I would have to see more proof that the cats are bad. Bad cats don't get better. Bad cats get worse.

So the lights would come on and stay on if the cats were bad?

Toyota Service : I just had a customer with a similar problem here an hour ago on a Tundra.
Toyota Service : Yes. On and stay on
Toyota Service : Before I even thought about cats, I would want to see the response of the sensors. If you have a faulty sensor, the cat code can be set. The lights blinking might be the beginnings of a bad sensor. To be certain, I would need to see some real time readouts.
Toyota Service : What I would do if I were you: see if you can find a fuel additive called "BG-44K". Fill the tank, pour the entire can into the tank, and drive it, run the fuel out as fast as you can. Then take it and get it rescanned. I use the BG product, it seems to improve cat performance by cleaning out the system. Def worth a try before I spent a grand on a unsupported guess.

OK...I'll try that and if it doesn't help there's another Toyota dealer not too far from here and I can take it to them, not tell them about the earlier diagnosis and just see what they say. thanks for your time.

Toyota Service : Ok. You are welcome
Toyota Service : Thanks for choosing Just Answer today. I trust my input will be found to be beneficial. If so, please choose to accept my answer via the accept button on your screen. Thanks again.
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