Potential Symptoms
Symptoms of a P2185 may include:
- Very poor fuel economy
- A no-start condition
- Vehicle may start but run very poorly, blow black smoke, run very rough, and misfire
- MIL illumination
Causes
A P2185 code may indicate that one or more of the following events have occurred:
- A poor connection to ECT sensor #2
- An open in the ground circuit between ECT sensor #2 and the PCM
- A short in the voltage supply between the sensor and the PCM
- A faulty PCM (less likely)
- A faulty temperature sensor (internally shorted)
Possible Solutions
First, if you have access to a scan tool, check the reading from coolant sensor #2. Is it reading a logical number? If so, the problem is likely intermittent. Perform a “wiggle” test by shaking the connector and harness on the sensor while watching the reading on the scan tool. Look for dropouts. Dropouts would indicate a poor connection. If the scan tool reads an illogical temperature, check the resistance of the temperature sensor. If it is out of specifications, replace it. If it is within specifications, unplug the sensor and, using a fused jumper, connect the two terminals of the connector together. The temperature reading should now be maxed out above 250 degrees F. If not, there is likely an issue with the ground circuit or the voltage supply.
Check for the 5-volt reference voltage at the connector. Also check for ground at the connector. If you do not have 5V ref. and/or ground continuity, check for them at the PCM connector. If you have them at the PCM connector, then repair the open or short circuit between the PCM and the sensor. If you do not, remove the offending wire from the PCM, then check for the appropriate voltage at the PCM pin. If it is present now, repair the short on 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 do not rule out these other possibilities. If you are unsure how to diagnose a PCM, do not attempt it.