P1374 — Engine Temperature Light Monitor Failure

P1374 — Engine Temperature Light Monitor Failure. A fault in the engine cooling and temperature control. Short, gentle driving to a shop is usually possible. Typical causes: low coolant level or air in the system, failed cooling fan or fan relay, water pump or radiator issues.

For Ford vehicles

ignition spare - cylinder 4 – fault detected

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution and watch the temperature gauge. A thermostat stuck open mainly costs fuel; any sign of overheating means stop immediately — driving an overheating engine destroys head gaskets and worse.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P1374 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the engine cooling and temperature control for damage, corrosion, chafing or poor contact.
Subsystem check Watch coolant temperature in live data during warmup — it should climb smoothly to operating temperature.
Subsystem check Check coolant level and feel upper/lower radiator hoses to verify thermostat operation.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P1374 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P1374 (parts and labor, USD, independent shop rates): Cooling system repair (pump, fan, radiator): $300–$1,200; Replace the thermostat: $150–$400; Replace the coolant temperature sensor: $100–$300. Overall, fixing P1374 usually costs between $100 and $1,200. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How much does it cost to fix P1374?

Cooling system repair (pump, fan, radiator) — $300–$1,200; Replace the thermostat — $150–$400; Replace the coolant temperature sensor — $100–$300. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

How do I diagnose P1374 myself?

Start with a scan: confirm P1374, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the engine temperature light monitor, and verify the suspect component against live data before buying parts.

What is the most common cause of P1374?

The most common causes are: low coolant level or air in the system, failed cooling fan or fan relay, water pump or radiator issues.

What are the symptoms of P1374?

Drivers most often notice: Check Engine Light on, cooling fans running constantly, temperature gauge reads low or never reaches normal, increased fuel consumption.

What does OBD2 code P1374 mean?

Your engine relies on a closed-loop cooling system to maintain proper operating temperature, and the ECU continuously monitors this process through data from multiple sensors. P1374 triggers when the powertrain control module detects that the engine temperature monitoring system is not behaving as expected under specific driving conditions. Rather than flagging a single bad reading, the module waits for the fault pattern to repeat before logging the code and illuminating the check engine light.

The temperature light monitor specifically tracks whether the engine is warming up correctly and staying within safe limits during operation. When the coolant temperature sensor, related wiring, or supporting components like the water pump and cooling fans send inconsistent or out-of-range data, the ECU recognizes the discrepancy and sets P1374. This code falls under the powertrain category, meaning it affects engine or transmission management rather than body electronics or chassis systems.

When technicians retrieve P1374, they also capture freeze frame data—a snapshot of engine load, RPM, coolant temperature, and vehicle speed at the moment the fault occurred. This information is critical because it tells you exactly what conditions triggered the code, allowing you to reproduce those circumstances during testing rather than guessing blindly.

Common Symptoms of P1374

Check engine light remains illuminated after startup
Cooling fans run continuously even when the engine is at normal operating temperature
Temperature gauge reads abnormally low or fails to climb to the normal operating range
Noticeable increase in fuel consumption due to the engine running too cool
Overheating warnings appearing on the dashboard in more severe cases
Poor or insufficient cabin heating performance
Engine taking longer than usual to reach operating temperature

What Causes P1374?

Faulty coolant temperature sensor sending incorrect readings to the ECU
Wiring problems in the temperature sensor circuit including corrosion, chafing, or loose connectors
Malfunctioning cooling fan or fan relay preventing proper heat dissipation
Water pump issues reducing coolant circulation through the engine
Stuck or failing thermostat allowing coolant to flow at the wrong times
Radiator problems such as blockages or internal leaks
ECU software issues requiring a reflash or update from the dealer

How to Diagnose P1374

Connect a professional OBD2 scanner and confirm that P1374 is stored in the ECU memory. Save all freeze frame data before clearing anything—this snapshot records exactly what the engine was doing when the fault first appeared.
Scan for any related diagnostic trouble codes. Often, a failing sensor or wiring issue will generate multiple codes simultaneously, and addressing the root cause clears everything at once.
Check manufacturer technical service bulletins using your vehicle identification number. Some vehicles have known software calibrations or updates that resolve intermittent temperature monitoring faults.
Visually inspect the wiring harness and electrical connectors associated with the engine cooling system. Look for damaged insulation, bent pins, moisture intrusion, and secure attachment at each connection point.
Monitor live coolant temperature data on the scanner while the engine warms up. The temperature should rise smoothly and plateau around 195–210°F. Erratic readings, flatlines, or failure to climb indicate sensor or circuit problems.
Clear the code and perform a complete drive cycle that reproduces the conditions captured in the freeze frame. If P1374 returns, you have confirmed an active fault rather than a one-time glitch.

Repair Options for P1374

Replace the engine coolant temperature sensor — parts and labor: $100–$300
Replace the thermostat and housing assembly — parts and labor: $150–$400
Repair or replace cooling system components such as the water pump, radiator, or cooling fan motor — parts and labor: $300–$1,200

Total Repair Cost for P1374

The actual cost to fix P1374 depends entirely on which component is responsible for the monitoring failure. The most affordable scenario involves simply replacing a faulty temperature sensor, while the most expensive repairs involve major cooling system components like the water pump or radiator. Labor rates at independent shops typically range from $80–$120 per hour depending on location. Most P1374 repairs fall between $100 and $1,200 when accounting for both parts and professional installation. Always pursue proper diagnosis before purchasing replacement parts—replacing every possible component adds up quickly and rarely fixes the underlying issue.

Can You Drive with P1374?

Drive with caution and keep a close eye on your temperature gauge. A thermostat stuck in the open position primarily affects fuel economy and cabin comfort, but any sign of overheating demands immediate stopping. Continued driving with an overheating engine can destroy head gaskets, warp cylinder heads, and cause catastrophic engine damage that far exceeds the cost of a simple repair. If the gauge enters the red zone or you see steam, pull over safely and have the vehicle towed rather than risking major engine failure.