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MANUFACTURER REFERENCE

Hyundai code references.

Explore documented code cases for the models, years and powertrains identified by the manufacturer.

Hyundai diagnostic guides

Find a guide by code

Hyundai P0128: when the answer is a thermostat, and when it is software

Compare the 2017 Elantra thermostat campaign with the 2018 Elantra GT and 2019 Veloster 1.6T software campaign before authorizing a repair.

These manufacturer documents cover specific vehicle conditions. Keep the complete scanner display and match the stated model, year and powertrain before using a case.

Browse the separate generic OBD-II reference

Model documentation

Only models identified by the cited manufacturer material are listed.

Elantra GT

2018

Veloster

2019

Elantra

2017

Documented code cases

Each document retains its own vehicle scope and complete code displays.

P0128 campaign diagnostic-logic update

T3T case.

Documented scope: 2018 Elantra GT PD; 2019 Veloster JS · 1.6L Turbo

Displays: P0128

Compare campaign branches.

VIN-specific; distinct from TLL.

Read the diagnostic case guide