What is a Pre-Fix Firmware?Following Dieselgate, there were several updates and revisions made by manufacturers to remedy their non-compliance. One of these updates was new firmware for the TCU (Transmission Control Unit). "Pre-Fix Firmware" is often referenced when discussing firmware revisions before and after the Dieselgate fixes. It is debated as being a better driving experience for many owners, but most vehicles have been updated with no official way of reverting back to the older firmware versions. Even today, some revisions are inaccessible. TuneZilla's database is always growing, and we are currently able to offer pre-fix firmware for several supported box codes (TCU versions). If you are currently happy with the way your transmission operates, there may be no reason to revert to an older firmware version and a TCU tune may be all you need.How do I switch to Pre-Fix Firmware?When FlashZilla Pro reads a TCU for the first time, your Box Code / current firmware version will be used to find a compatible "Pre-Fix" firmware version. If one is available, you will be prompted to choose whether you would like to retain your existing firmware version ("IGNORE") or revert to a pre-fix firmware version ("SWITCH FIRMWARE"). Firmware differs from a Tune. Our Tunes are built on-top of your TCU's current firmware version. Before purchasing any TCU tune files, you should determine if pre-fix firmware suits your needs as changing firmware versions after tuning may incur additional re-calibration fees.This prompt will only appear the first time you read your TCU. If you decline to switch firmware versions, or have already read your TCU prior to this feature being released, you will not be asked again. If you decide to switch at a later date, or are an existing FlashZilla Pro user, please open a ticket to have us manually enable this feature for you. Additionally, if you already have a TCU tune and wish to try reverting to an older firmware version, we can transfer any existing InstaTunes to the pre-fix firmware. If you wish to transfer your custom or modified TCU tune, there will be a small re-calibration fee to re-build your tune for the different firmware version.Which box codes are supported?If you were prompted by TuneZilla Portal about this feature, then your TCU is currently supported! Otherwise, you can compare your current firmware number / version with the table at the end of this section to see if this feature supports your TCU. To find your current TCU firmware version, please connect your FlashZilla Pro to your vehicle, and take note of the firmware version shown on the Tuning page (as shown below). If you don't have a FlashZilla Pro, you can use VCDS or OBD11 to see your TCU's firmware.Supported Box Codes VersionsThis list will be updated as we release support for new box codes, check back soon to see when this feature supports your TCU.Vehicle (Approximate)Box Code / FirmwarePre-Fix Status (see note)2011-12 Audi Q7 3.0L TDI0C8927750SSupported2013-16 Audi Q7 3.0L TDI0C8927750AQSupported2011-12 VW Touareg 3.0L TDI0C8927750GSupported2013 VW Touareg 3.0L TDI0C8927750AKNot Supported *2014 VW Touareg 3.0L TDI0C8927750CFSupported (Added 2024-10-18)2015 VW Touareg 3.0L0C8927755Supported2015-16 VW Touareg 3.0L0C8927755RSupported2013-14 Porsche Cayenne 3.0L TDI0C8927749FCComing Soon (Stock and Autobahn available on request)2015-16 Porsche Cayenne 3.0L TDI0C8927769DHSupported (Added 2024-10-18)Last updated 2024-10-18Note: Box Codes / Firmware Versions listed as "Not Supported" require a donor TCU with pre-fix firmware before we can offer this feature. If you have a pre-fix TCU with one of these firmware versions please reach out to us to see how you could earn a complimentary tune!Frequently Asked QuestionsQ: Is this a tune?No this is not a tune! This feature flashes your vehicle with official firmware from the manufacturer. These files contain no modifications by TuneZilla and are provided as is. Tunes only modify certain sections of the TCU's firmware, and many characteristics and behaviours of a TCU's firmware will persist even after flashing a tune.Q: Does this cost money? Do I need to purchase a tune first?No, the pre-fix firmware flashing is available to all FlashZilla Pro users* at no additional cost! We didn't make this firmware and we don't think it's fair to charge money for it! You can flash your TCU with this pre-fix firmware without purchasing a TCU tune.Protip: FlashZilla Pro is not VIN locked and can be used on multiple vehicles, or shared between multiple users. Purchase one for yourself here: https://tunezilla.com/fzproQ: Can I go back to the dieselgate version?Yes you can go back, however, his process must be manually initiated by a TuneZilla Staff member. This is currently limited to 1 revert-request per vehicle, subsequent requests may incur a $50 fee at our discretion. To start this process please open a ticketQ: My vehicle is already pre-fix why am I getting this message?This feature also tries to update older pre-fix firmware versions to the latest pre-fix version. This ensures you have the latest manufacturer bug-fixes, this version is also prioritized by our calibrators and generally has better InstaTune support.Q: Why is this change detectable by the manufacturer?While this feature uses official and unmodified firmware, TuneZilla and FlashZilla Pro make no attempt to conceal the downgraded firmware version. A connected scan tool can and will detect the change in firmware versions. If you suspect that this could be a problem, please proceed at your own discretion -- TuneZilla does not take responsibility for any warranty complications as a result of using this feature.Q: My Vehicle / Box Code is listed as "Coming Soon" or "Not Supported", what now?If your vehicle is listed as "Coming Soon" it means we're working on the final touches for your vehicle to ensure our users have the best experience possible. Come back to this blog in a few weeks to see if it's been released, or open a ticket for an ETA or notification.If your vehicle is listed as "Not Supported" it means we're currently missing the pre-fix firmware for your TCU. We will require a donor TCU with pre-fix firmware before we can offer this complimentary downgrade feature for our other customers. If you or someone you know has a pre-fix TCU labelled as "Not Supported" please reach out to see how you (or someone you know) could earn a complimentary TCU tune (or the equivalent value off your ECU tune).Q: Can I use this feature if my TCU is already tuned by TuneZilla?Yes you can switch even if you're tuned, however there are a few things to note:This process must be initiated manually by a TuneZilla Staff memberAfter flashing, your vehicle's TCU will be stock and your tune will need to be reflashed. In most cases tunes can be transferred within a business day, but additional delays may apply depending on tune / calibrator availability (see table below)Our tunes are based on your original firmware version, flashing to a different firmware will unlink all existing tunes from your vehicle. In most cases your tune can be replaced with an equivalent pre-fix version, however, additional charges may apply depending on the type of tune (see table below)InstaTune / Off The ShelfModified InstaTune (see note)Custom TuneIf you used our InstaTune platform to create your tune then in most cases we can replace your tune with an equivalent pre-fix InstatuneIf you requested revisions to an existing InstaTune file, then these modifications will need to be recreated for the pre-fix firmwareCustom tunes must be recreated for the pre-fix firmware version. This is subject to calibrator approval, and may require new data logsFree of chargeAvailable immediately where equivalent tunes are availableRe-calibration fee at the discretion of the calibratorAvailability depends on calibrator schedule$100 Re-calibration fee upon calibrator approvalHeavy participation and data logs requiredNote: To avoid extra fees we recommend trying the pre-fix InstaTunes before requesting modifications.To start this process, or request more information please open a ticketQ: Can I use this feature if my TCU is tuned by someone else?Yes, you can use this feature to downgrade your TCU's firmware, however there are a few things to note:As with tuning we strongly recommend you return your TCU to stock and unlink any existing tools before flashing with FlashZilla ProAfter flashing, your vehicle's TCU will be stock and your tune will need to be reflashed.Depending on your tuner, your existing tunes may not be compatible with the pre-fix firmware version and in some cases flashing your tune will update your TCU back to your original firmware version.Consult your tuner before downgrading or switch to TuneZilla to avoid the hassle and save 15%. 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