# 66 error code
**URL:** https://community.electricforum.com/t/66-error-code/6503
**Category:** GEM Forum
**Created:** [November 24, 2016, 3:45pm UTC](https://community.electricforum.com/t/66-error-code/6503 "2016-11-24T15:45:41Z")
**Posts on this page:** 20
**Page:** 3
### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [August 10, 2019, 11:06pm UTC](https://community.electricforum.com/t/66-error-code/6503/42 "2019-08-10T23:06:02Z")
Took it out for a 3 mile run, all was good until the last half mile and everything shutdown, No dash display, no nothing, then error -15. Reset the master breaker and all was good from there. I don’t think this is controller related. It might be the cheap Chinese BMS, I am about ready to remove it and see if things stabilize. When I got back to the house I checked the voltage over BT and I was at 96V so I was defiantly not low on voltage as the error said.
Bottom line, I think WE fixed the controller !!!
I can;t add anymore replies until someone else posts so I added it here:
@Inwo
Bypassed the BMS, left it connected but also added a cable directly from -B of the battery to the -B controller cable, so I can still montior the cells and balance if needed but the BMS can’t stop the car from running or stop a charge, but I don’t need it for that.
Drove 5 miles, no issues. Things are looking peachy!!
Awesome work Dave!! and thanks for the insight.
@diymatt @milleniumdawg - Looks like maybe we can fix these 66 errors.
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### Author:  [@milleniumdawg](https://community.electricforum.com/u/milleniumdawg)
#### Post date: [August 11, 2019, 10:22pm UTC](https://community.electricforum.com/t/66-error-code/6503/43 "2019-08-11T22:22:30Z")
This is weird, I Let the car for a day, with the master breaker off, went out and tried it, worked perfectly… who knows!!!
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [November 12, 2019, 2:23am UTC](https://community.electricforum.com/t/66-error-code/6503/44 "2019-11-12T02:23:14Z")
@grantwest
Look here for -66 help.
> **[10pcs/lot STP80NF12 P80NF12 TO-220 120V 80A: Amazon.com: Industrial &...](https://www.amazon.com/10pcs-STP80NF12-P80NF12-220-120V/dp/B07Z68KPXH/ref=sr_1_1?keywords=p80nf12&qid=1573525644&s=industrial&sr=1-1)**
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 12, 2019, 2:53am UTC](https://community.electricforum.com/t/66-error-code/6503/45 "2019-11-12T02:53:04Z")
@grantwest @Inwo
Don’t know where the above came from? But Grant if you need a set of mosfets I have a set on the shelf - all yours. Was going to fix a T4 but went AC instead.
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### Author:  [@grantwest](https://community.electricforum.com/u/grantwest)
#### Post date: [November 12, 2019, 3:10am UTC](https://community.electricforum.com/t/66-error-code/6503/46 "2019-11-12T03:10:37Z")
I have a 2008 that has a T-4 that is gonna stay DC my 2016 is gonna be the AC beast
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 12, 2019, 3:26am UTC](https://community.electricforum.com/t/66-error-code/6503/47 "2019-11-12T03:26:58Z")
So you don’t need the Mosfets?
I also have two T-4’s for sale…
I can’t wait to see your 16’ -
My 08’ will soon be “Beast 2 - Tesla powered” 🙂
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### Author:  [@grantwest](https://community.electricforum.com/u/grantwest)
#### Post date: [November 12, 2019, 4:29am UTC](https://community.electricforum.com/t/66-error-code/6503/48 "2019-11-12T04:29:38Z")
I’m gonna crack open my T-4 and see if the Mosfetts are blowen
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [November 12, 2019, 5:16am UTC](https://community.electricforum.com/t/66-error-code/6503/49 "2019-11-12T05:16:53Z")
Pictures above should help. Use ohmeter on all combinations of the three leads. Look for a difference between devices. Zero ohms between any is a sure sign of shorted mosfet.
You can also use “diode test” anything lower than 400mv is most likely a short circuit.
Be mindful of to-220 tab mounting, if insulated electrically from heatsink, and heat conductive pad or grease on same.
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 12, 2019, 1:47pm UTC](https://community.electricforum.com/t/66-error-code/6503/50 "2019-11-12T13:47:17Z")
@grantwest
I had a hell of a time testing them while still on the board. If it is a -66 error just replace all six Mosfets and you should be good.
Like I said, I have them (eight I think) and the insulators still in the box for digikey if you need them.
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 12, 2019, 2:00pm UTC](https://community.electricforum.com/t/66-error-code/6503/51 "2019-11-12T14:00:34Z")
Or send it to me and I can try and fix it up, if you are not good with the old soldering iron.
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 16, 2019, 6:42pm UTC](https://community.electricforum.com/t/66-error-code/6503/52 "2019-11-16T18:42:05Z")
Congrats to @grantwest - he is now in the “I fixed the -66 error code on a T4” club.
Good work Mr. Grant!!!
@grantwest
@Inwo
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### Author:  [@DelThink](https://community.electricforum.com/u/DelThink)
#### Post date: [November 19, 2021, 8:21am UTC](https://community.electricforum.com/t/66-error-code/6503/53 "2021-11-19T08:21:00Z")
I purchased an E825 today, 20 minutes in to driving it down a hill it started flashing and now I have error code -66.
I would like to have it repaired (sounds like mosfets) or find a PERMANENT FIX.
Is there a solution for this issue?
Thanks in advance.
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 19, 2021, 2:37pm UTC](https://community.electricforum.com/t/66-error-code/6503/54 "2021-11-19T14:37:04Z")
What controller are you running?
All the repair info is in the tread. The repair is permanent if done correctly, or you can replace the controller.
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### Author:  [@DelThink](https://community.electricforum.com/u/DelThink)
#### Post date: [November 22, 2021, 8:36am UTC](https://community.electricforum.com/t/66-error-code/6503/55 "2021-11-22T08:36:32Z")
Hello, I have a 2002 Gem E825 with a code 66, Are you able to replace the mosfets? Thank you, Scott
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### Author:  [@DelThink](https://community.electricforum.com/u/DelThink)
#### Post date: [November 22, 2021, 8:38am UTC](https://community.electricforum.com/t/66-error-code/6503/56 "2021-11-22T08:38:08Z")
Thanks! it is a Gem T2.
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### Author:  [@MikeKC](https://community.electricforum.com/u/MikeKC)
#### Post date: [November 22, 2021, 2:17pm UTC](https://community.electricforum.com/t/66-error-code/6503/57 "2021-11-22T14:17:04Z")
Oh, I think you will want to replace your controller - I don’t think anyone here has repaired a T2.
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### Author:  [@JarJarJava](https://community.electricforum.com/u/JarJarJava)
#### Post date: [November 22, 2021, 3:41pm UTC](https://community.electricforum.com/t/66-error-code/6503/58 "2021-11-22T15:41:05Z")
@DelThink
You can try FSIP.biz, they rebuild controllers.
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### Author:  [@DelThink](https://community.electricforum.com/u/DelThink)
#### Post date: [November 22, 2021, 5:41pm UTC](https://community.electricforum.com/t/66-error-code/6503/59 "2021-11-22T17:41:55Z")
Thanks! Talking with them now.
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### Author:  [@DelThink](https://community.electricforum.com/u/DelThink)
#### Post date: [December 9, 2021, 12:46am UTC](https://community.electricforum.com/t/66-error-code/6503/60 "2021-12-09T00:46:20Z")
Okay, I pulled my controller out and sent it to FSIP they rebuilt it for $440. I just put it back in and I still get error code 66. What are my options here? Thanks in advance.
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### Author:  [@JarJarJava](https://community.electricforum.com/u/JarJarJava)
#### Post date: [December 9, 2021, 1:07am UTC](https://community.electricforum.com/t/66-error-code/6503/61 "2021-12-09T01:07:31Z")
A couple gallons of gasoline and a match?
Call FSIP about the repair. You wouldn’t be the first member on here who had to send their “repaired” controller back to FSIP to be re-repaired. 20 year old high amperage DC controllers, sometimes they miss things. Sucks, but not sure if there is anyone out there that rebuilds these.
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