Technical Description of OBD-II Trouble Code
The circuit for Engine Coolant Temperature Sensor #2 is experiencing a high input.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to all vehicles manufactured from 1996 onwards (VW, Ford, Dodge, Chevrolet, etc.). While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The engine coolant temperature (ECT) sensor is a thermistor that is screwed into a coolant passage in the cylinder head. The resistance of the sensor is high when the coolant temperature is low, and it decreases as the coolant temperature increases.
The powertrain control module (PCM) supplies a 5-volt reference and a ground to the sensor. The PCM monitors the voltage drop to determine the coolant temperature. If the ECT reads a temperature below freezing after the engine has been running for more than a few minutes, the PCM identifies a circuit fault and sets this code. Alternatively, if the PCM determines that the sensor resistance is outside of the specified range, this code is set.
An example of an Engine Coolant Temperature ECT sensor
Note: This DTC is essentially the same as P0118, but the difference with this code is that it refers to the #2 ECT sensor circuit. Therefore, vehicles displaying this code have two ECT sensors. Make sure you are diagnosing the correct sensor circuit.
Potential Symptoms
Symptoms of a P2185 code could include:
Causes
A code P2185 may indicate that one or more of the following has occurred:
Possible Solutions
First, if you have access to a scan tool, check the reading of the #2 coolant sensor. Does it display a logical number? If so, the problem is likely intermittent. Perform a “wiggle” test by moving the connector and harness to the sensor while observing the reading on the scan tool. Look for any drop-outs, as they would indicate a faulty connection. If the scan tool displays an illogical temperature, check the resistance of the temperature sensor. If it is outside of the specified range, replace it. If it is within the specified range, unplug the sensor and use a fused jumper wire to connect the two terminals of the connector. The temperature reading should now exceed 250 degrees F. If it does not, there is likely a problem with the ground circuit or voltage supply.
Check for a 5-volt reference voltage at the connector. Also check for the presence of ground at the connector. If you do not have a 5V reference and/or ground continuity, check for these at the PCM connector. If you have them at the PCM connector, then repair any open circuits or shorts between the PCM and the sensor. If you do not have them, remove the problematic wire from the PCM and then check for the proper voltage at the PCM pin. If it is now present, repair the short in the circuit. If it is not present after removing the wire and checking the pin, replace the PCM.
NOTE: Usually, P2185 indicates a faulty temperature sensor, but it does not rule out these other possibilities. If you are unsure how to diagnose a PCM, do not attempt to do so.
Related ECT sensor circuit codes: P0115, P0116, P0117, P0118, P0119, P0125, P0128, P2182, P2183, P2184, P2186
