P0128 on Lincoln
Coolant Thermostat Below Regulating Temperature
P0128 on Lincoln vehicles indicates coolant thermostat below regulating temperature. Au7o has documented this code across 1 Lincoln model — most commonly on LS. 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 Lincoln range from $300 to $900, 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 Lincoln by Model
Lincoln LS(1 issue)
- Lincoln LS 3.9L V8 Coolant Crossover Manifold Leak2000-2006
The 3.9L AJ V8 (Jaguar-derived) in 2000-2006 Lincoln LS suffers coolant crossover-tube failure where the plastic manifold connects the heads at the rear of the engine. Leaks present as coolant dripping at the back of the engine, smell of coolant after shutdown, eventually overheating. Often co-fails with the plastic thermostat housing and degas bottle.
Looking for P0128 on a different make?
View P0128 across all makes →Frequently Asked Questions
What does P0128 mean on Lincoln?▼
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 Lincoln specifically, this code is documented across 1 model.
What causes P0128 on Lincoln vehicles?▼
Common causes on Lincoln: 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 Lincoln?▼
Repair costs on Lincoln range from $300 to $900, depending on the specific model and root cause.
Which Lincoln models have P0128 documented?▼
Au7o has documented P0128 on 1 Lincoln model: LS.