This code indicates the powertrain control module has detected an implausible signal from the engine coolant temperature (ECT) sensor, meaning the reading is out of expected range or doesn't correlate with other temperature sensors and engine operating conditions. It typically triggers when the sensor reports a temperature that contradicts startup conditions or changes at an impossible rate, rather than indicating a complete electrical circuit failure.
The thermistor inside the sensor may drift out of calibration or respond too slowly to temperature changes, sending voltage signals outside the expected range for current operating conditions.
Trapped air or insufficient coolant creates uneven temperature distribution around the sensor, causing intermittent or erratic readings that violate the PCM's rationality checks.
High resistance from corroded terminals, damaged wiring, or poor ground connections alters the voltage signal returned to the PCM, making the temperature appear out of range.
An engine that warms up too slowly or fails to reach operating temperature can trigger this code when the ECT reading remains too low for too long compared to predicted values.
While possible, a faulty control module misinterpreting a good signal is statistically unlikely and should only be considered after verifying the sensor, wiring, and cooling system integrity.
No. The PCM is rarely the cause of this code. This code almost always stems from a faulty sensor, wiring issues, cooling system problems, or air pockets. Replacing the PCM without first verifying the sensor and circuit integrity is usually a misdiagnosis.
Short distances are possible, but prolonged driving is not recommended. Incorrect temperature readings can cause the engine to run rich, wasting fuel and potentially contaminating the engine oil with fuel dilution or damaging the catalytic converter.
This usually indicates an underlying issue such as air pockets in the cooling system, a stuck thermostat, or intermittent wiring corrosion that wasn't addressed. Ensure the cooling system is properly bled and the connector pins are clean.
P0116 indicates a rationality or performance problem where the signal is present but implausible, while P0117 (low input) and P0118 (high input) indicate specific voltage readings outside the absolute electrical range, typically pointing to short or open circuits.