CVTz50  |  CVT diagnostics with ELM327

In order to communicate with the majority of CVT transmissions, CVTz50 requires a good ELM327 interface ("a good version 1.4 or 1.5"). The CVT diagnostic protocol is more complex than standard engine diagnostics, so it requires more functionality from the ELM327. This means that many "bad v2.1" interfaces are able to connect to the engine; however, they are missing features required to establish a connection with the transmission and other control modules. Some "bad" interfaces are still able to provide limited connectivity to CVT in compatibility mode (compatibility mode can be enabled by choosing the option "ELM327 v2.15 workaround" in the CVTz50 menu), however, advanced functionality will not work (like clearing "CVTF deterioration date", reading engine brake level, list of previously cleared DTCs, some monitoring parameters).

The fastest and most reliable way to get a proper ELM327 v1.5 is to buy it from a local store. Check it immediately with CVTz50 or CVTz50 DEMO and get your money back if it is unable to connect to the transmission. The only disadvantage is that the price of the interface will be higher than in online stores.

It is also possible to buy a good ELM327 interface via eBay or AliExpress by searching for the keywords ELM327 PIC18F25K80 (PIC18F25K80 is the name of the chip inside the majority of "good" adapters). The problem is that some sellers are still shipping "fake" interfaces even if they mention the name of the correct chip in the item description, especially sellers offering the lowest prices. So before placing an order, it is necessary to check with the seller whether their product really has a proper version 1.5 chip and is built on appropriate hardware. Sample query to a seller: Is your ELM327 1.5 built on original Microchip PIC18F25K80? What is the frequency of the crystal oscillator, 4 MHz or 16 MHz? Does it support commands ATAL and ATPPS?

The casing of good and bad interfaces is the same (many variants of cases exist however all of them can have fake components inside) so you need to look at the internal components. Many online stores provide pictures of disassembled devices which make it possible to recognize obvious fakes (though pictures in online shops are not always real).

"Good," "real version 1.5" ELM327 interfaces are built on the PIC18F25K80 chip produced by Microchip. As a rule, such interfaces are properly listed as "version 1.5" in online stores. Android application ELM327 Identifier after analysis of such device show that the interface supports all commands of ELM327 protocol till version 1.4.

"Bad" (or fake) interfaces are built on cheap microcontrollers like STM32F042, YM1130, BK3231Q, 25K80 QBD327 and other unknown chips often hidden under black drop of special varnish. Such interfaces are usually recognized as "Chinese version 2.1", however many unfair sellers are selling these as v1.5. Moreover, when connected to diagnostic software, poor interfaces can report version 1.5 so they are "fake v1.5" (actually they can show any number there). If "bad" interface is not trying to trick the user, then ELM327 Identifier will show that many v1.4 commands are not supported. However, if a fake ELM327 is programmed to cheat diagnostic software, ELM327 Identifier can show same result as for good interface or even better.

Pay special attention to a new kind of fake adapter introduced in 2017, built on the QBD327 chip relabeled as PIC18F25K80. Such relabeled chips have the following characteristics:

• Microchip logotype (M) on fake chip is blurred (while original chip has clear and sharp logo)
• The third line of the label on the fake chip has the string 14309MP or 1643URE or 1850AAJ; the original chip has different strings with the encoded production date
• Fake chip uses crystal oscillator with frequency 16.000MHz (usually located near the chip); original PIC18F25K80 requires crystal oscillator 4.000MHz
• Fake ELM327 does not support command ATPPS; a good ELM327 recognizes the ATPPS command and responds with a list of hex numbers (ATPPS can be sent to the adapter using "Custom commands" in CVTz50 DEMO).

To open the adapter for checking the internal components, you can use a screwdriver or a knife; the cover is held in place by clips:

Good ELM327 interface: Microchip PIC18F25K80 and a 4 MHz crystal oscillator.
It may be built on one PCB (like on the picture), or on two or three PCBs soldered together

Generally, a good ELM327 interface (microchip PIC18F25K80 and crystal oscillator 4MHz), however this specific variant with PCB KA2019+switch can be turned on only while engine is running.

Bad ELM327 interface: fake microchip PIC18F25K80 with label 14309MP and crystal oscillator 16MHz

Bad ELM327 interface: Microchip STM32 (except Vgate iCar Pro and similar which are priced above average)
Sometimes such interfaces can work with limitations in the mode "ELM327 v2.15 compatibility"

Bad ELM327 interface: unknown chip hidden under a drop of varnish

Bad ELM327 interface: 2 chips with erased labels. Sometimes 16-pin chip has label "ℼ"

Bad ELM327 interface: unknown chip hidden under a drop of varnish

Bad ELM327 interface: unknown chip hidden under a drop of varnish is on the back of circuit board

The following models cannot be easily disassembled, but they are usually good

Vgate iCar Pro: good. Price starts from $15.

ObdLink LX (or MX, MX+): very good. Price starts from $50.

vLinker FD, MC, MS: very good. Price starts from $20.

Konnwei KW903 Bluetooth 4.0/5.0: usually good, however works only in Bluetooth Low Energy mode, which is not compatible with older Android devices. Price starts from $10.

Viecar 4.0: good. Price from $15.

Veepeak OBDCheck VP01, VP11, BLE: are reported to be good. Price from $15.