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Ez pass problems

My ez pass is not being recognized since placing it in my model s, was fine in the BMW. Worked when holding it out the passenger window. Anyone else experiencing this, any theories?

The window is coated and will not allow transponder signals through, except for the black painted area next to the rearview mirror mount. Mount your transponder there and it will work fine.

The UV and infrared blocking coating on the windshield could be interfering with the low power transponder signals, which might explain why it works when you hold it outside the car. Also, if the ez pass has a battery, you might try a fresh one and see if it makes a difference. If you are mounting it on the windshield, keep it as far away as possible from the rear view mirror.

Oops on the rear view mirror thing. There are electronics in the mirror that could be a possible source of interference, but if others have had good luck mounting in the black painted area next to the rearview mirror mount, go for it.

that's pretty much what the black painted area is for

Ty, I'll try tomo

I spent an hour at the E-Pass service center in Orlando... they have a test toll gate setup in the parking lot. In the end we tie-wrapped a old-school bumper type (usually reserved for armored cars) to the front grill. That was after I paid the 30 toll violations I ran up since starting back to work after Christmas.

I'm hoping when the service dude comes with my 21" rims he can remove the grill and I can put it back there.


@GaryOrlando - so the new credit-card-sized "permanently affix to the windshield" type SunPass is no good? I know from my recent trip to Miami airport that the new slim 'two sucker' removable ones don't seem to work.

It might be possible to get an EZ pass tag for the front license plate (which is required in Texas). That seems like a better solution than trying to jury-rig something inside the nose cone.

While I would prefer not having the front license plate at all, if I do have to have one, might as well get some benefit from it...

The EZ Pass mounted to your front license plate is the way to go - it is unobtrusive and it works.

I had the same issue with my EZPass. I had one of the old (larger) units and tried mounting it in the painted area to the right of the rear view mirror mount with no luck (and 3 violation notices). I ended up switching to the license plate mounted version, which works fine though it's somewhat clunky looking.

I've heard that the newer, smaller EZPass units can be mounted next to the mirror bracket successfully but haven't done this myself.


Curious what folks are doing when there are roads that tolls are waived if you carpool? In Norther California there are quite a few freeways like that and you are supposed to put your EZPass in a special bag so it wont charge you. Clearly in the nose cone/license plate that wouldn't work.

Keep it inside the car and hold it out the side window when you pass the toll checking point ? ;)

Hmm, I assume that the same problem will arise in Southern California with Fasttracks to use on the 73, 91, 110, etc. then ..!?

Except that here in SoCal, if your pass isn't detected, they just take a picture of your plate and charge you as if the pass was detected (as long as your plate is registered). They usually won't fine you, but I think that the CHP can still pull you over if the pass isn't affixed to the winshield.

My FasTrack transponder works fine. I placed it just below the rearview mirror mount.

After an hour at the e-pass service center they gave me (no $ after I let the boss drive) an old school external transponder. We went through their test gate with each of the "regular" transponders and nothing worked. Apparently these are the "last resort" which normally go on Bentley's and armored cars.

The Tesla service dude was nice enough to mount it under the nose cone when he was at my place to install the spoiler and 21" rims. It's out in the elements though so I don't recomend trying it with the one that's meant for inside.

The cone actually comes off really easy but I didn't want to break it trying myself.

I had been using the SunPass sticker and then the portable one with suction cups... I had $41 in unpaid tolls when they brought up the account.

Beware that if you use a SunPass and it doesn't work, and you drive through an E-Pass toll, the plate picture doesn't get transfered to E-Pass and you can get a violation.

Well this is a problem. NJ is pretty hard to navigate without EZ Pass.

Hmmm... so after reading these threads and others on TMC I went to the SunPass service Center in Boca Raton to test my transponder.

For me, it did NOT work in the black dotted area next to the mirror.
It DID work just to the right of that in the plain glass area - see image below.


Others have reported that SunPass also works below the mirror. So far I haven't seen anyone say that it works in the dotted area next to the mirror, but one user has reported that EZ-Pass worked in that area.


"Somewheres within several inches of the dotted area. Give or take."

I'm not sure if this is universal, but New York's MTA EZPass has a green pass type of account for EVs that gives very large discounts when used off peak. $4.75 versus $13.00.

Get the license plate EZ Pass.

Was able to get my EZ Tag to work by sliding it under the right side of the rear view mirror mount and sliding the top half into the seam between the windshield and the roof.

The fit is snug enough that it doesn't appear that I'll need to peel the backing off the tag and glue it to the windshield.

And in this location, it's almost completely invisible, only able to see the right 2/3 of the bottom half of the tag from the inside and on the outside, it's almost completely hidden by the black dots.


Thanks for the photo and location advise. How many times did you get a chance to successfully check the location shown in the photo while at the Boca Rotan servic center?



Larry - good question - that's what I'm a bit concerned about. At the SunPass service center they used a hand-held device to test.

I drove through the I95 express lane yesterday and the transaction has NOT shown up on my SunPass activity. Looks like it isn't solved yet.

I think I need to go back to SunPass. I don't think they have a real test gate, but I'm going to check.

I'm also going to test moving the device below the mirror - folks have said that works for some devices.


Indiana requires ez pass be mounted. I need to find the place to mount it. Anyone figure this out yet?

Outside the windshield?

So far the only place I have found to mount my EZ Pass is in my wife's car....

I actually had to take a ticket and pay CASH last time I went to a entrance to the PA turnpike. It was so old school.

Went back to the SunPass service center today. They've now given me a transponder that can be attached to the front license plate holder or grill. Since I have neither of those I need to speak to Tesla Service and see if there's a mounting solution behind the nose cone.

Got the new external transponder mounted today. After talking to the TM service tech we decided to try and mount it behind the nose:

It is held on by double-sided tape. The zip ties are there just in case.

Haven't been through a toll plaza yet to see if it actually works...

nickjhowe: let us know when you test that. thanks.

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