A failing engine coolant temperature sensor that has an internal break in its winding or a worn wiper contact.; Corroded, loose, or backed-out pins in the sensor connector or the ECM connector.; A chafed or broken wire in the sensor circuit that intermittently shorts to ground or opens when the engine moves.; Coolant contamination or low coolant level causing the sensor tip to be exposed to air instead of liquid.; A faulty thermostat that sticks open, preventing the sensor from reaching normal operating temperature and causing erratic readings.; Electrical interference from a nearby component, such as an ignition coil or alternator, inducing noise into the sensor signal.; A failing ECM driver circuit, though this is rare and should only be suspected after all wiring and sensor tests pass.

DTC codes / P01xx · Fuel and air metering / P0119

P0119Engine Coolant Temperature Circuit Intermittent

Q: What does code P0119 mean?

Engine Coolant Temperature Circuit Intermittent. P0119 means the engine control module (ECM) has detected an intermittent signal from the engine coolant temperature (ECT) sensor circuit, where the voltage reading momentarily drops out or jumps instead of changing smoothly. The ECM sets this code when the intermittent fault is severe enough to affect its calculations but not constant enough to trigger a hard-failure code like P0118.

P0119 means the engine control module (ECM) has detected an intermittent signal from the engine coolant temperature (ECT) sensor circuit, where the voltage reading momentarily drops out or jumps instead of changing smoothly. The ECM sets this code when the intermittent fault is severe enough to affect its calculations but not constant enough to trigger a hard-failure code like P0118.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

The check engine light may be the only thing you notice, with no drivability complaints at all.
The temperature gauge on the dashboard may flicker, drop to cold, or swing erratically while driving.
The engine may briefly run rich or rough when the signal cuts out, especially during warm-up.
You might see poor fuel economy or a slight hesitation because the ECM is guessing the coolant temperature.
In some vehicles, the cooling fan may run constantly or not at all when the signal is lost.
Cold-start idle quality may suffer if the intermittent signal confuses the ECM's fuel enrichment strategy.

Common causes, most likely first

A failing engine coolant temperature sensor that has an internal break in its winding or a worn wiper contact.
Corroded, loose, or backed-out pins in the sensor connector or the ECM connector.
A chafed or broken wire in the sensor circuit that intermittently shorts to ground or opens when the engine moves.
Coolant contamination or low coolant level causing the sensor tip to be exposed to air instead of liquid.
A faulty thermostat that sticks open, preventing the sensor from reaching normal operating temperature and causing erratic readings.
Electrical interference from a nearby component, such as an ignition coil or alternator, inducing noise into the sensor signal.
A failing ECM driver circuit, though this is rare and should only be suspected after all wiring and sensor tests pass.

How to diagnose and fix it

Scan all modules for stored and pending codes, then clear codes and test-drive while watching live ECT data to confirm the intermittent dropout.
Inspect the ECT sensor connector and wiring for corrosion, loose pins, or chafing, and wiggle-test the harness while watching the live data.
Measure the sensor's resistance with a multimeter at cold and hot temperatures and compare to the manufacturer's specification chart.
Check the coolant level and condition, and pressure-test the cooling system if the sensor is not fully submerged.
Backprobe the sensor signal wire at the ECM and monitor voltage while flexing the harness to isolate an intermittent open or short.
Replace the ECT sensor if resistance testing or live data shows erratic behavior, then clear codes and verify the repair with a road test.
If the sensor and wiring test good, check for a faulty thermostat or electrical interference before condemning the ECM.

Intermittent ECT faults that fool good technicians

A sensor that tests perfectly on a cold engine can still fail intermittently once hot, so always test resistance at operating temperature as well as cold.
The ECM often substitutes a default coolant temperature value when the signal drops out, which can mask the fault and make the engine seem to run fine during a short test drive.
Wiggle-testing the harness while watching live data is the single most effective way to catch a chafed wire that only acts up on bumps or during engine movement.
A sticking-open thermostat can cause the ECT signal to drop unexpectedly as coolant temperature falls, setting P0119 even though the sensor itself is healthy.
Aftermarket sensors with poor calibration are a common cause of repeat intermittent codes, so a known-good OEM-quality replacement is worth the extra cost.

Can I keep driving with P0119?

You can usually drive short distances to a repair shop, but avoid long trips or heavy load because an intermittent coolant temperature signal can cause poor fuel mixture and overheating protection may be compromised. If the temperature gauge is erratic or the engine runs rough, stop driving and have it diagnosed promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.