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Technical Description of OBD-II Trouble Code
Malfunction in the Circuit of Engine Coolant Temperature Sensor 2
What does that signify?
This diagnostic trouble code (DTC) is considered generic because it applies to all 1996-newer OBD-II equipped vehicles (e.g. Vauxhall, VW, Ford, Dodge, etc.). Specific troubleshooting and repair steps may vary slightly depending on make/model.
The ECT (Engine coolant temperature) sensor is essentially a thermistor that alters resistance with temperature. Usually a two wire sensor, it receives a 5 volt reference from PCM (Powertrain Control Module) and a ground signal to PCM. This is distinct from a temperature SENDER (which typically operates the dash temperature gauge and functions similarly to the SENSOR, but it’s a different circuit than what a P2182 is referring to).
As the coolant temperature changes, the resistance on the ground signal to the PCM also changes. When the engine is cold, the resistance is high. When the engine is warm, the resistance is low. If the PCM detects a voltage condition that appears abnormally low or high, P2182 will be triggered.
An example of an Engine Coolant Temperature ECT sensor
Note: This DTC is essentially identical to P0115, however the difference with this code is that it pertains to the #2 ECT circuit. So vehicles displaying this code means they have two ECT sensors. Make sure you are diagnosing the correct sensor circuit.
Symptoms
Symptoms of a P2182 DTC code can vary from nothing other than the “check engine” light illumination, to one or more of the following:
Causes
Usually the cause can be traced to a faulty ECT sensor, however that doesn’t exclude the following:
Possible Solutions
First, visually inspect the #2 ECT sensor for damage to wiring or connector and repair as necessary. Then, if you have access to a scanner, determine the engine temperature. (If you don’t have access to a scan tool, using the dash temperature gauge may not be an effective way to determine coolant temperature. This is because the P2182 code is referring to the #2 ECT SENSOR, and the dash gauge is operated by, usually a one-wire SENDER. Basically a different sensor that the code doesn’t refer to.)
2. If the engine temperature is abnormally high, around 280 deg. F, that’s abnormal. Unplug the sensor on the engine and see if the signal drops to, say, negative 50 deg. F. If it does, then it’s likely that the sensor is faulty, internally shorted, causing a low resistance signal to be sent to the PCM. However, if you want to be certain that it’s the sensor and not the wiring, there are a couple of tests you can perform. With the ECT sensor unplugged, check for a 5-volt reference on the circuit with KOEO (Key on engine off). Additionally, you can check the resistance of the sensor to ground using an Ohm meter. The resistance of a normal sensor to ground will vary slightly depending on the vehicle, but generally, if the engine temperature is around 200 deg. F., the resistance will be approximately 200 Ohms. If the temperature is around 0 deg. F., the resistance will be over 10,000 Ohms. With this test, you should be able to determine if the resistance of the sensor matches the temperature of the engine. If it’s not accurate according to your engine’s temperature, then you probably have a faulty sensor.
3. Now, if the temperature of the engine according to the scanner is around 280 deg. F. and unplugging the sensor doesn’t cause the reading to drop to negative 50 deg. F, but it remains at the same high temperature reading, then you’ll need to repair the short on the signal circuit (ground) to the PCM. It’s shorted directly to ground somewhere.
4. If your temperature reading of the engine according to the scanner is showing negative 50 deg. F or so, (and you don’t live in the arctic!) unplug the sensor and check for a 5V reference present at the sensor.
5. If there isn’t, then check at the PCM connector for proper 5V reference. If it’s present at the PCM connector, then repair the open or short on the 5V reference from PCM. If there is no 5V reference present at the PCM connector, then you’re done with your diagnosis and you may have a PCM fault. 6. If the 5V reference circuit is intact, then check the ground signal to the PCM using the previous ground resistance test. If the resistance isn’t normal for the temperature of the engine, then measure the resistance of the ground signal to the PCM by removing the ground signal wire from the PCM connector. The wire should have no resistance when unplugged from the PCM to the sensor. If it does, repair the open in the signal to the PCM. If it doesn’t have any resistance on the ground signal wire and the resistance test of the sensor is normal, then suspect a faulty PCM.
Related ECT sensor circuit codes: P0115, P0116, P0117, P0118, P0119, P0125, P0128, P2183, P2184, P2185, P2186
Professional Service
Of course, we always recommend seeking professional mechanical assistance to resolve this issue. However, if for some reason this seems impossible, then we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
