P0128 on Nissan
Coolant Thermostat Below Regulating Temperature
P0128 on Nissan vehicles indicates coolant thermostat below regulating temperature. Au7o has documented this code across 1 Nissan model — most commonly on NV. This code means the engine isn't reaching its proper operating temperature within the expected time, so the coolant stays below the thermostat's regulating temperature. The computer estimates how warm the coolant should be (based on run time, airflow, and intake air temperature) and compares it to the actual reading. When the engine warms too slowly or never gets hot enough, P0128 sets. The most common cause is a thermostat stuck open, which can cause reduced heater output, poorer fuel economy, and higher emissions. Typical repair costs on Nissan range from $200 to $600, depending on the specific model and root cause.
Common Causes of P0128
- •Thermostat stuck open or opening too early
- •Faulty engine coolant temperature sensor
- •Low coolant level
- •Cooling fan running constantly (overcooling)
- •Wrong-temperature-rating thermostat installed
- •Corroded or loose coolant temperature sensor connector
- •Air pockets in the cooling system
- •Faulty PCM/ECM (rare)
P0128 on Nissan by Model
Nissan NV(1 issue)
- Radiator Plastic End Tank Cracking and Coolant Leak2012-2021
The Nissan NV cargo van uses a radiator with plastic end tanks that develop cracks from heat cycling and vibration inherent to commercial van use. The cracks typically form at the crimp joint between the plastic tank and aluminum core. The V8 NV 2500/3500 models are more susceptible due to higher operating temperatures, especially when loaded to capacity. A cracked radiator causes gradual coolant loss that can lead to overheating if not caught early.
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View P0128 across all makes →Frequently Asked Questions
What does P0128 mean on Nissan?▼
P0128 stands for "Coolant Thermostat Below Regulating Temperature." This code means the engine isn't reaching its proper operating temperature within the expected time, so the coolant stays below the thermostat's regulating temperature. The computer estimates how warm the coolant should be (based on run time, airflow, and intake air temperature) and compares it to the actual reading. When the engine warms too slowly or never gets hot enough, P0128 sets. The most common cause is a thermostat stuck open, which can cause reduced heater output, poorer fuel economy, and higher emissions. On Nissan specifically, this code is documented across 1 model.
What causes P0128 on Nissan vehicles?▼
Common causes on Nissan: Thermostat stuck open or opening too early, Faulty engine coolant temperature sensor, Low coolant level, Cooling fan running constantly (overcooling), Wrong-temperature-rating thermostat installed. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0128 on a Nissan?▼
Repair costs on Nissan range from $200 to $600, depending on the specific model and root cause.
Which Nissan models have P0128 documented?▼
Au7o has documented P0128 on 1 Nissan model: NV.