Hi, what's a quick fix for a limp mode issue

Replacing accelerator cable and gearbox cables would have no bearing on this, and replacing the fuel pump and injectors likely not going to help. Is the vehicle overheating? That is the place to start as overheating can cause Limp Mode.

Or you find a local auto electrician to connect a professional grade scan tool computer to check for Diagnostic Trouble Codes and historical data. It sounds like the dealership don't have a clue. A pro scan tool can record what happens when it goes into limp mode.

Make sure there is no air in the cooling system

https://www.fixya.com/cars/r29872074-vehicle_cooling_system_no_heat

https://www.google.com/search?q=2018+hyundai+h100+limp+mode+problems

https://www.google.com/search?q=auto+electrician+near+me

..

Check spark plugs/gap. I've had similar experiences as the spark plug wears and the gap gets too big.

the limp mode will not allow you to accelerate until you have fixed the problem and reset the ECM
Limp modes are not there to help ease you frustrations but to prevent costly repairs to the engine and transmission
fix it , reset it then you will have no need to go nuts

Probly a computr issue...dont guess on parts. Unplug it and clean pins..then plug back in..see if car reboots. If no git it scand but find anothr mech. Go to surecritic.com

First the output shaft/speed sensor is bad. Find it and replace it first. (it is on the outside of the transmission) This may correct your problem. But 4500 RPM at 20 MPH is not limp mode.

The only way to bypass this is to fix the issue. Your vehicle is in what is called limp mode. Vehicles go into this mode to protect your vital engine or transmission components from failing. Get as can tool and read the check engine light codes or get it to a shop ASAP.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_677dced97ad9bddf

One of the accelerator position sensors may be bad putting it into limp home mode . Have it scanned for codes and post them here .

check with scantool for fault code

Limp mode is what some vehicle computers go into when there is a problem with the engine or transmission which, if traveling at regular acceleration and speeds, may cause further damage. So, in "limp mode", the vehicle can get around, just not very fast. Engine may not go beyond a specific RPM, transmission may only use the higher gears.

Charlie

Yep ,sounds like limp mode ,should be in second gear.
Try,key on engine off,depress accelerator to floor 3 times within 5 seconds.Should reset trans.