Faulty engine coolant temperature sensor 3, with internal short to ground.; Damaged or chafed wiring in the sensor signal circuit, shorting to ground.; Corroded, loose, or disconnected electrical connector at the sensor.; Coolant contamination or sensor tip coated with deposits, altering resistance.; PCM internal fault causing incorrect voltage interpretation (less common).; Aftermarket sensor with incorrect resistance characteristics installed previously.

DTC codes / P01xx · Fuel and air metering / P01E5

P01E5Engine Coolant Temperature Sensor 3 Circuit Low

Q: What does code P01E5 mean?

Engine Coolant Temperature Sensor 3 Circuit Low. P01E5 indicates that the powertrain control module (PCM) has detected an abnormally low voltage signal on the circuit for engine coolant temperature (ECT) sensor 3, which is a third temperature sensor used on some engines for additional monitoring. The PCM expects a voltage within a specific range that corresponds to the current coolant temperature, and a low voltage typically means the sensor circuit is shorted to ground or the sensor's internal resistance has dropped.

P01E5 indicates that the powertrain control module (PCM) has detected an abnormally low voltage signal on the circuit for engine coolant temperature (ECT) sensor 3, which is a third temperature sensor used on some engines for additional monitoring. The PCM expects a voltage within a specific range that corresponds to the current coolant temperature, and a low voltage typically means the sensor circuit is shorted to ground or the sensor's internal resistance has dropped.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms.
Inaccurate or erratic coolant temperature gauge readings on the dashboard.
Poor fuel economy or rich-running condition because the PCM may default to a fixed temperature value.
Difficulty starting or rough idle when the engine is cold, as fuel enrichment may be incorrect.
Cooling fan may run continuously or not at all, depending on the PCM's failsafe strategy.
In rare cases, the engine may enter limp mode or overheat protection mode.

Common causes, most likely first

Faulty engine coolant temperature sensor 3, with internal short to ground.
Damaged or chafed wiring in the sensor signal circuit, shorting to ground.
Corroded, loose, or disconnected electrical connector at the sensor.
Coolant contamination or sensor tip coated with deposits, altering resistance.
PCM internal fault causing incorrect voltage interpretation (less common).
Aftermarket sensor with incorrect resistance characteristics installed previously.

How to diagnose and fix it

Use an OBD-II scanner to verify P01E5 and check for related codes; record freeze-frame data.
Inspect the sensor connector and wiring for corrosion, damage, or loose pins; repair as needed.
Measure the sensor's resistance with a multimeter and compare to the manufacturer's temperature-resistance chart.
Backprobe the sensor signal circuit at the PCM to check for a short to ground with the sensor disconnected.
If the sensor is out of specification, replace it with an OEM-quality part and clear the code.
Clear codes and perform a road test to confirm the repair; monitor live data for ECT sensor 3 voltage.
If the code persists after sensor and wiring checks, diagnose the PCM or consult a professional.

Why ECT Sensor 3 Codes Mislead

Sensor 3 is often a cylinder head temperature sensor or a second coolant sensor used for fan control or gauge operation, so its failure may not affect drivability but can cause misleading temperature readings.
A low voltage code can be set by a short to ground in the signal wire, which may be caused by a pinched harness near the engine block or exhaust manifold, not just a bad sensor.
Some vehicles use a thermistor whose resistance decreases as temperature rises; a low voltage reading can therefore indicate an overheated engine rather than a circuit fault, so always verify actual coolant temperature with an infrared thermometer.
After replacing a sensor, the PCM may need a relearn procedure or a drive cycle before the code will clear, and simply clearing codes without fixing the root cause will lead to a repeat failure.
A failing thermostat or low coolant level can cause the sensor to read incorrectly and set a low voltage code, so cooling system health should be checked before condemning the sensor.

Can I keep driving with P01E5?

You can usually drive with this code, but monitor the temperature gauge closely and avoid heavy loads or long trips until repaired. If the gauge shows overheating or the engine runs poorly, stop driving and seek service immediately.

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.