My 07 mazda6 as four codes u0101,u0155 u0121,u0073,u0100 and stuck in 3rd gear please help

Do you know what U code's Are ? Do you have service info. ? Any module on the vehicle can cause a no start , GMLAN Hi & Lo .
2016 Traverse No start GM Lan A sensor that is on the 5 volt ref. circuit could bring down the Data bus . Your best bet , take your vehicle to a guy like in the video . Before you repalce parts you don't need , plus the BCM would need to be programmed . Anti-theft system - key's would need to be programmed too.

HDM module ??????? No such module .
DTC U0100 00: Lost Communication With Engine/Powertrain Control Module (ECM/PCM)
DTC U0101 00: Lost Communication With Transmission Control Module (TCM)
DTC U0121 00: Lost Communication With Electronic Brake Control Module (EBCM)
DTC U0140 00: Lost Communication With Body Control Module (BCM)
DTC U0151 00: Lost Communication With Restraints Control Module
DTC U0155 00: Lost Communication With Instrument Panel Cluster (IPC) Control Module
DTC U0164 00: Lost Communication With HVAC Control Module
DTC U0168 00: Lost Communication With Vehicle Theft Deterrent (VTD) Control Module
DTC U0170 00: Lost Communication With Passenger Presence System (PPS)
DTC U0184 00: Lost Communication With Radio
DTC U0186 00: Lost Communication With Audio Amplifier
DTC U0194 00: Lost Communication With Digital Radio Receiver (DRR)
DTC U0198 00: Lost Communication With Communication Interface Module (OnStar®)
DTC U0209 00: Lost Communication With Heated Seat Module (HSM)
DTC U0214 00: Lost Communication With Remote Function Actuation (RFA)

These are all the modules onyour vehicle - no hdm module .

All these " U " codes are communication issues amongst modules. These modules communicate on bus wiring from one to another. You have a communication issue with one or more modules. You will most likely have to have the vehicle proffessionaly scanned with a vehicle scan tool to be able to identify the source of this communication issue. You may have a bad module/wiring/power/ground issue to be repaired

Disconnect batt see if it clears. Or unplug computr..clean connection pins...see if unit reboots. Dirty brake fluid can ruin abs module. To pinpoint du a datastream w a factory scantool and not at a dealer. Code readers dont give u numbrs for decision.

U0100 - Lost Communication with ECM/PCM "A"
U0155 - Lost Communication with Instrument Panel Cluster (IPC) Control Module
U0101 - Lost Communication with TCM
All of them are Geniric Codes 4 Mazda, I would say who ever was working on the car last, posobly forgot or missted 1 or 2 connection
plugs along the way near the last repairs. So just trace yr last steps 2 see if ther any unpluged connectors, cos looks like they all are part of same chane in that line.
P2187 - Sys To Lean at the idle Bank 1
Hope that helpes you. Good luck.
Tony D:-)

U0100 means lost of communication with ECM/PCM
U0101 means lost of communication with TCM

A U Code means a module is not communicating. A technician needs to find out what module is not communicating and make sure it is getting power, ground and can communicate, If any one is missing it may be in the wiring. If all are present the module is bad.
A scan tool will help in this process.

I got the same problem. u ever figure it out? ive cleared codes and there the same. light on cluster lit up . plus some time after pulln away from stop car goes five mph. turn off start up drives fine. im about to burn this thing.

These are transmission control module can communications codes. ealer will need to repair these for sure.

U0121 Communication error to ABS HU/CM