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Toyota Window Fogging from injector replacement?

I live in Fairbanks, AK and have a 2000 Toyota Sienna van. Recently, I took it to the local dealer and had all the injectors replaced. They replaced all six injectors and a coil and took ten days to do it. The interior windows now fog over in no time when I am driving. I have to run the defroster at full blast to see adequately.

It isn’t so much a matter of the temperature, there just seems to be a lot more moisture inside the vehicle than ever before. I park in a heated garage and leave the windows open, there’s almost no humidity in the garage, but those windows fog over before I’ve gone more than half a mile.

I don’t know if it can be related, but my fuel economy is down by about 20% since having the work done, too.

The rude and hostile treatment I got from the dealer makes me reluctant to talk directly with them unless I have some information in hand to bolster my certainty that they screwed something up. Again.

Any suggestions?



With the engine running and the Defroster on, raise the hood and try to determine if the air conditioner compressor is running. It’s possible that during this repair they may have inadvertently disconnected a wire connector. The compressor needs to run during defrost operation.

As to fuel mileage being down, that could be related to the prior repair but it’s impossible to say without seeing the car. Maybe a vacuum line dislodged or an intake boot clamp not tight? A vacuum leak below the throttle plate could cause a faintly rough idle and a leak above the throttle plate may not be noticeable at all but the engine computer would notice it and try to increase the fuel/air mix to compensate for it. Lower fuel mileage could occur.

The thing that raises a red flag to me is the part about replacing all of the injectors replaced. Injector failure is rare and replacing all of them points to someone wild guessing in regards to a diagnostic problem. Tack on the part about them having the vehicle for 10 days and it looks even more suspect.

Maybe you can glean some little bit of info out of that anyway.

The first thing that I would suggest that you check is the recirculation control for the HVAC system. When this control is set to the “recirculate” position, rather than the “fresh air” position, it will produce exactly the symptoms that you describe. This control could have been inadvertantly moved by you, a passenger, or even a mechanic.

In light of what they did and DIDN’T do, I think you NEED to seriously shop for a reputable independent tech/shop.

I wouldn’t be hesitant to spread the word as to the work? they charged you for or the treatment.

That said, NOT all Toyota dealers are alike. I got excellent service and personal treatment when I dealt with the Toyota dealer I bought my Matrix from.

In the back of your mind, you’re thinking," are they just being extra nice until the warranty wears off/". Perhaps they are like that all the time.

Other customers I spoke with in the service department said they were always treated with respect and so far the repairs were fair and just.

FYI, OK4450 is a very well respected and knowledgeable tech with his own shop and many years of experience. (Ay least on this site he is! ha ha ha) You can take what he says to the bank.

TEN days to change a coil and six injectors? YOW! (Will you learn to blow your own horn? ha ha ha)
I’ll bet you’re walking around in a t-shirt drinkin’ cool ones while we’re freezin’ our butts and by tomorrow I’m going to have 6" of new snow to shovel. YUK!

Thanks for the advice, all. I am going to apply it in a few minutes, as soon as I Google to find out what the air conditional compressor looks like.

The shop said two of my injectors were bad, but they told me they would have to replace all of them or the repair would not work. Does that make sense? It cost me $1400 in parts alone (and I found out that Toyota will sell them to me directly for about $800, and that’s retail), but the dealer said they won’t honor a warranty on parts unless I buy directly from them. If I go to Toyota for parts, I don’t get a parts warranty.

I used to use a local small garage when I drove domestic vehicles. In fact, I called them and asked if they would do the work on my Sienna. They told me to take this repair to the dealer. I think they just don’t like working on Toyotas because this is the second repair they’ve sent me to the dealer for. Frankly, the fact that they know their limits means a lot more trust from me. I’d rather have a shop where I talk to a mechanic and tell him what’s happening and have him tell me what he thinks he’ll need to do, rather than the dealer where I have to talk to a Service Advisor who doesn’t know much about cars and won’t let me talk to someone who does. I think I just need to get a referral from my usual mechanic to someone who likes Toyotas and isn’t the dealer.

Okay, rant over.

Thanks again. I’ll post again to follow up when this problem is fixed.


Air conditioner, not conditional. Whee. I knew what I thought I was typing.


As embarrassing as it is to admit it, this was the solution to the fogging problem. I didn’t even think of it because I always keep it in the fresh air position. Don’t know why they moved it.

Still don’t know what’s up with the unusual rate of fuel consumption. I’ll keep looking, but at least I can see out of the windows, now!

I feel rather simple, but at least it was a simple problem


For the mileage problem I recommend you check to see if the temperature sensor for the ECU is working like it should be. If it isn’t the ECU may think the engine isn’t warming up after running for a while and the fuel mixture will stay too rich.
I have to wonder if this wasn’t the real problem instead of the injectors. Like OK4450, my senses are saying something isn’t right here. You may want to get in touch with the Toyota area representative and tell him about the injector prices. If what you say about the parts prices is correct you were clearly ripped off and Toyota needs to know about that.

Could the temperature sensor for the ECU cause engine misfires? That’s what they told me was happening and said it was two of the injectors (I think they said #2 and #4, but don’t hold me to that). They then said I’d have to replace all six injectors because it doesn’t work to replace just two.

The price for parts from the Toyota Parts Center was a little over $800 for six injectors and a coil. The price from the local dealer was a little over $1400. I have the paper on both and the dealer acknowledged that the retail price I showed him was accurate. He gave me some hogwash about having to pay for stocking (what stocking? If he doesn’t have the part in stock, he doesn’t have to stock it!) a couple of million dollars’ worth of parts so having to make a profit. But that’s a lot of profit on not a lot of parts.

I’ll see if the Toyota website has any sort of way to contact the area representative.

As you can tell, my expertise in modern automotives ends where I stick the key in and go. Boy am I glad there is a place like this to come ask for advice!


In my opinion the misfires might happen if the fuel mixture is too rich but I think it is more likely to happen if it is too lean. Others here may be able to answer that better than myself. Did the work they performed fix the misfire problem or is it still occuring?

As far as the prices for the new injectors, there is no way the dealer can justify that. They most likely had to order them and that is part of the reason the repair took so long. Tell them you don’t think the price they charged for the parts is justified and you want the phone number for the Toyota area rep. Maybe they will reconsider giving you a partial refund if they see you want to take some action on this. That is clearly taking advantage of you and things like this is what gives dealer services a bad reputation. Toyota will not like to hear that.

As you learned, fogging of the windows had nothing to do with injector replacement. The lesson here is to always look for the most likely solution, not a very remote cause and effect situation that is not logically connected to the problem at hand.

Or, as they teach in US medical schools regarding how to logically diagnose a patient’s symptoms:

“If you hear hoof-beats coming up behind you, you should first suspect horses, rather than zebras”.

You were looking for zebras.

Other than the fact you should ignore Roadrunners comment about me being well respected and knowledgeable (barely), it does not make sense to replace all of the injectors even if 2 of them were legitimately bad. If you have 4 out of 6 bad I would say yes and 3 out of 6 is a maybe.

If you had 2 out of 6 injectors bad (as in real bad or dead) then the car should have been running very badly with a constant CEL problem.
If the injectors were marginally bad then the worst symptom should be a rough idle or possibly a hesistantion on take off.

The worker is so used to being inside the customer’s cars that they forget to respect the controls and they set them wherever they want them. It’s bad customer service when you forget to respect him and his property.

Symptoms were an intermittent “check engine” light and some hesitation on acceleration, such as I associate with ice in the gas. I did pour a bottle of Heet in the gas (that’s always worked for me before) and, on the suggestion of a mechanic, a bottle of Techron fuel system cleaner. Didn’t do the job, though.

Hmm, I came on to ask about the fog and seems I’m getting information I should have asked for two weeks ago. Only, I thought I could trust the dealer since my usual shop sent me to them. Duh.

The Service Advisor was very clear in telling me that if I only replaced the two bad injectors the job would almost certainly have to be done again because it doesn’t work to replace only two. Does that make any sense to you?

Thanks again for all the information. Loads to try to understand and learn from.


Yes, I was looking for zebras. However, it seems that I’m getting some very valuable education about the issue for which I was charged so much by the dealer, so it is well worth looking like a dummy in order to find out what I have about the injectors and about how to deal with unscrupulous dealer tactics.

Go ahead and call me stupid, so long as you help educate me! I’m sure I’ve seen about ten different ways to say that and it all holds true.


Well, with water under the bridge it’s going to be impossible to ever tell what transpired. Considering the totally bogus story about HAVING to replace all of the injectors or else and the fact this was related to you by a service writer would not lend much credibility to the story at all.

I understand why service writers do this. They do not want to appear mechanically illiterate to the customer so they blather their way through the day.

A temperature sensor failure could cause a performance problem but then again. a failure of the temp sensor will not pick out 2 injectors to screw upl; it will affect them all.

Considering the bogus stories, 10 days of vehicle imprisonment, and a coil replacement I’m almost of the opinion the problem may have been nothing more serious than a misfiring spark plug. A misfiring plug can kill an ignition coil and a failing coil can also foul out a spark plug. Kind of a vicious circle.

For what it’s worth, I can count on one hand the number of failed injectors I’ve seen on “normal” F.I. systems; with normal being defined as electrically operated fuel injectors. In other words, most of the civilized world.
The only chronic injector problems I’ve ever encountered were on the older VWs, SAABs, BMWs, Benzes, etc that were equipped with CIS injection. Crummy injector spray patterns, etc. were a way of life with those.

Wished I could be more specific but just offhand I have the feeling that someone was doing some expensive guessing on your car.

And one addendum. If those guys replaced all of the injectors without replacing the fuel filter you should never let them touch your car again.

I don’t think that anyone is calling you stupid.

I do think that you were probably naive to accept the “replace ALL of the injectors” diagnosis, but since your own mechanic sent you to the dealership, I am not surprised that you were taken in by their solution to the problem.

And, in regard to the fogging of the windows, most likely your angst about the overall situation prevented you from clearly and calmly analyzing the cause and effect scenario with the fogging.

The invoice does not show a fuel filter on it. How bad is this? Should I have someone else put a new one in?


That should have been done before replacing the injectors. In fact, it would have been a good step before diagnosing the injectors as the problem. Yes, I would have it changed.