I have a 2000 hyundai accent and it has a fault code of P0128 what does that mean

Tidied up the question a bit.
Question moved to sub category

Did the inability to start happen right after you put the new battery on? Did you reset the security system?

P0343 HYUNDAI Code Camshaft Position Sensor 'A' Circuit ...

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Repair Information for P0343 Hyundai code. Learn what Camshaft Position Sensor 'A' Circuit Range/Performance means, location and how to repair?

Dirty connections and grounds!

P0626 OBD-II Trouble Code: Generator Field/F Terminal ...

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P0626 means there's a fault on the generator field circuit due to a faulty alternator, battery, wiring, or poor communication between control module.

P0342 HYUNDAI Code Camshaft Position Sensor 'A' Circuit ...

https://www.autocodes.com > p0342_hyundai
Repair Information for P0342 Hyundai code. Learn what Camshaft Position Sensor 'A' Circuit Low Input Bank 1 Or Single Sensor means, location and how to ...

Here is what I found on P0128 code:
- Leaking or stuck open thermostat
- Low engine coolant level
- Insufficient warm up time
- Faulty engine coolant temperature sensor
- Engine coolant temperature sensor harness is open or shorted
- Engine coolant temperature sensor circuit poor electrical connection
When is the code detected?
The engine coolant temperature does not reach to specified temperature even though the engine has run long enough.
P0128 Hyundai Description
Coolant thermostat (coolant temperature below thermostat regulating temperature). Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.
I WOULD TAKE IT TO A DIFFERENT REPAIR SHOP, ONE THAT HAS YOUNG MECHANICS THAT UNDERSTAND TROUBLESHOOTING CODES AND SEARCHING YOUR CAR COMPUTER FOR SOFT AND HARD CODES THAT MAY BE RELATED TO THIS CODE. YOUR COMPUTER SOMETIMES KEEPS A HISTORY OF CODES.
GOOD LUCK
Read more: http://engine-codes.com/p0128_hyundai.html#ixzz3JpRiZ9eN

try the cam sensor too

You may have a problem with the speed sensor or the OD solenoid, you will need the dealer to scan the Transmission control module for fault codes.

P1407 EGR No Flow Detected is what the code means. You will have to locate, replace or repair the EGR valve. I recommend the Haynes Repair manual as a reference.

P0717 - Input/Turbine Speed Sensor "A" Circuit No Signal
P1529 - Customer Snap Shot Request

• NOTE_P1529 is a generic code which is issued by the TCU to tell the ECU to turn on the CEL. It means nothing by itself and is usually included with other TCU codes.

Look for air bleeds, sounds like the coolant has air pockets. And ALWAYS check coolent level with heater set to full heat, or water valves would be closed, and blocking coolant...

2001 accent gl 1.6, p1123 code comes on. how can I repair it myself?

This problem of misfire in the damp is commonly caused by faulty HT leads or electronic coils. Check all plug leads first.

P1123 fault code is often associated with a faulty MAF on Hyundai cars. However first start at the air inlet tube, checking for obstructions or leaking vacuum hose which may also cause this code to show.

take the warning light bulb out or stick a bit of black tape over it