P0128 on Hyundai Vehicles
The engine takes too long to warm up, which almost always points to a thermostat stuck open. P0128 →
7Complaints mentioning the code
#4Rank among 11 brands
1.0%Share of Hyundai DTC complaints
In NHTSA owner complaints we analyzed for Hyundai, P0128 was mentioned 7 times.
Most mentioned models
| Hyundai Sonata | 3 | |
|---|---|---|
| Hyundai Elantra | 1 | |
| Hyundai Elantra Gt | 1 | |
| Hyundai Santa Fe | 1 | |
| Hyundai Tucson | 1 |
Model years mentioned
Components named in these complaints
- Engine (7)
- Fuel/propulsion System (2)
- Power Train (1)
- Electrical System (1)
Reports with a crash: 1 · fire: 0 · injuries: 1
Often appears together with
P0301
Powertrain
Cylinder 1 is repeatedly failing to fire. The cause is almost always its coil, plug, injector…
Moderate
P0302
Powertrain
Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant…
Moderate
P0303
Powertrain
Cylinder 3 is misfiring. Check whether it misses at idle or under load before you blame…
Moderate
P0420
Powertrain
The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly.
Low
P0605
Powertrain
The memory holding the engine computer's program failed its integrity test – try one reflash…
Moderate
Possible causes
- Thermostat stuck partly open or opening too early
- Coolant temperature sensor reading lower than the actual temperature
- Low coolant level or an air pocket around the sensor
- Radiator fan running constantly (stuck relay or faulty fan control)
Related codes
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.