Ez pass problems

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?

DannyM | 30 December, 2012

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.

stevenmaifert | 30 December, 2012

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.

stevenmaifert | 30 December, 2012

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.

tork | 30 December, 2012

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

sbern18 | 30 December, 2012

Ty, I'll try tomo

GaryOrlando | 15 January, 2013

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.


nickjhowe | 16 January, 2013

@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.

bp | 16 January, 2013

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...

JThompson | 16 January, 2013

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

BostonMike | 16 January, 2013

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.


GreenDot | 16 January, 2013

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.

jkirkebo | 16 January, 2013

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

michael.delune | 16 January, 2013

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.

jinglehyme | 16 January, 2013

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

GaryOrlando | 21 January, 2013

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.

DanD | 21 January, 2013

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

nickjhowe | 22 January, 2013

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.


Brian H | 22 January, 2013

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

jrb | 27 January, 2013

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.

JThompson | 27 January, 2013

Get the license plate EZ Pass.

bp | 27 January, 2013

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.

Larry Chanin | 27 January, 2013


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?



nickjhowe | 27 January, 2013

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.


art | 28 January, 2013

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

Brian H | 28 January, 2013

Outside the windshield?

bhs1 | 28 January, 2013

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.

nickjhowe | 7 February, 2013

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.

nickjhowe | 9 February, 2013

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...

appljd | 9 February, 2013

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

nickjhowe | 9 February, 2013

Sure will. Will get them to do a hand-held test on Monday. Will try and hit the turnpike too.

The external transponder costs the same ($26) as a mobile, windshield-mounted suction cup transponder - in fact I traded my suction cup one in for this one for zero cost. The TM guys said they'd tried the suction cup version in the nose cone and it didn't work.

Brian H | 10 February, 2013

Unless TM has developed RF-impermiable plastic, it's gotta work!

nickjhowe | 17 February, 2013

I finally had an opportunity to test the externally mounded transponder today - worked like a charm!!!

This is by far the best solution. You can even do it yourself if you have the nerve to pop the nose off. Or you can ask TM to do it - they did it for free for me.

If you use a plastic tool you can insert it where the arrow points below and lever the nose cone. It should start to come away from the car. It is held on by a dozen or so automotive push clips. It takes a bit of force, but it does come off.

Uploaded with

We used double-sided tape to stick the transponder to the front face of the steel bumper, then used cable ties just in case. You could drill/tap the bumper itself. Your call.

bobinfla | 18 February, 2013

@nickjhowe: Thanks for solving this mystery, definitely gonna go this route. I'm always nervous about automotive clip fasteners. don't know once you unhook will they rebook again, so will touch base with service center about helping install it. Then I guess I need to call Sunpass about the dozen or so tolls I owe them while figuring out all the locations that the suction cup transponder doesn't work.

bradslee | 18 February, 2013

I have two CA Fastrak transponders shared by our three cars. If I hold the transponder up inside my BMW 335i, passing the toll has no problem at all. However, doing the same inside my MS, the transponder could not be recognized. Since it is not an option for me to permanently attach one of the transponder to MS, I wonder if I hold the transponder outside the window each time passing the toll, will it work?

dortor | 18 February, 2013

has anyone tried - or can they confirm/deny - the transponder in the "back window" works?

just a random thought.

rkang | 18 February, 2013

My New Jersey EZ Pass (green colored) works right under the rear view mirror.

hsadler | 18 February, 2013

"I wonder if I hold the transponder outside the window each time passing the toll, will it work?"

Open the roof and hold it up.

bradslee | 18 February, 2013


Thanks for your tip and will give a try (hopefully the wind won't blow my transponder away!). -:)

nickjhowe | 18 February, 2013

@bobinfla - Byrone at the Dania service center used to work on Porsches, BMWs,... he says the clips on the S are the best he's seen. Other mfg's clips always used to break; he says TMs are much more resilient. But better safe than sorry...

@dortor - might work on the Turnpike/I-95, but I also use it at Miami Airport parking. There you have to pull under the sensor and get the transponder read before the gate will rise. In the back window I think the roof would block the line of sight - but it might work.

Mark Z | 12 March, 2013


This location is working for my battery operated FasTrak.

Under the hatch with proper angle and alignment through the rear window, yet not visible from the outside. The recessed area makes it easy to find and mount with the Velcro provided.

Mark Z | 14 March, 2013

The mirror mount location WORKS PERFECTLY. Here is a photo:

I received a response from "The Toll Roads" today. Please DISREGARD MY SUGGESTION of the rear hatch location. While it works and it's not on the glass, the Highway Patrol could be upset. Here is the reply:

"Thank you for contacting The Toll Roads.

In accordance with the California Vehicle Code, it is not permitted to place the transponder in the rear window.

The internal transponder may be placed on the lower left-hand side or right-hand side of your windshield or behind the rear view mirror where it will not obstruct your sight while driving.

At times, we have found that the polarized windshields have prevented the internal transponder from reading at all times. Therefore, it may be necessary to replace your internal transponder with an external one.

This recommendation is presented in situations when the internal transponder fails to read while properly mounted and generates a significant number of tolls which are paid by the license plate number instead of the transponder number.

The external transponders mount directly to the front license plate brackets and are secured with tamper-resistant screws. A special tool is provided in order to remove/affix the external transponder."

I am 3146 | 16 March, 2013

The small NJ EZPass works great when affixed just above the rear view mirror to the plastic rear view mirror base. It has worked perfectly on the N J Turnpike and Commodore Barry Bridge.


Uploaded with [URL=][/URL]

Brian H | 16 March, 2013

If you want to post images here, use HTML, not BB Code.

Brian H | 16 March, 2013
pablodds | 17 March, 2013

I live in Florida and so far I was successful in mounting my transponder right below the rear view mirror base. The transponder I used is a pretty narrow long rectangular one that I bought online from sunpass for $25. I will test it out this whole week. We will see if it works all the time.

noel.smyth | 17 March, 2013

Confirmed today that the location below the rear view base works well. I'll be mounting it there. thanks for the research on this!

DouglasR | 17 March, 2013

If you have a long narrow device as we have in Washington state (shape of a popsicle stick), it works well on the top horizontal surface of the rear view mirror itself. A good fit, and nearly invisible.

jdb | 18 March, 2013

@ pablodds, please let us know if you get the Florida Sunpass transponder to work on regular basis through the windshield. I have not much luck. Have adopted a temporary fix-putting the small transponder with the suction cups on the inside surface of the driver side outside mirror when using sunpass routes. The suction cups adhere well to the flat metal surface, no problems with falling off, even on bumpy roads, and easy to remove. But of course need to remove when parking for security, and not reommended for rainy days.