Testing the ECT/CHT sensor Resistance: One way is to measure the resistance of the sensor at different engine temperatures and compare the readings to the specifications listed in the service manual.ĭisconnecting the ECT sensor will show as -40 degrees on the scan tool. There are several ways to test the ECT sensor you can find the correct way in the service manual. The ECT sensor connector must be checked for damaged pins or corrosion. The coolant level always has to be checked first when dealing with cooling system problems. Ways to test the engine coolant temperature sensorīecause the tip of the sensor has to be immersed in coolant, the low coolant level or air pockets inside the cooling system can cause the signal from the sensor to be incorrect. Of course, considering that the ECT sensor is not an expensive part, it's often recommended to be replaced if suspected to be malfunctioning. Many Check Engine light codes related to the ECT sensor could also be caused by other reasons, such as a bad thermostat or issues with the cooling system, including even a leaking head gasket. The repair involves installing a new sensor and retrofitting a few related parts. The bulletin SI M17 06 12 for some R55, R56, R57 and R58 MINI Cooper/CooperS vehicles describes a similar problem with the corrosion inside the engine coolant temperature (ECT) sensor that can cause inaccurate engine temperature reading. Depending on the severity of the corrosion, the connector and the CHT sensor must be cleaned or replaced. For example, the Ford service bulletin TSB 11-10-5 describes the problem in the 2010-2012 Fusion, Escape, Transit Connect, as well as Mercury and Lincoln branded vehicles with the 2.5L engine: water contamination in the sensor connector can cause codes P1285, P1299Īnd/or P0128. The harness must be repaired to correct the problem.Ĭorrosion at sensor terminals or connector can also cause sensor-related faults. If any of the wires are damaged or shorted, it could cause many different trouble codes, including the ECT sensor codes P0117 and P0118. The GM service bulletin PI0631F for the 2012-2013 Chevrolet Impala mentions the issue with the wiring harness rubbing on the front right side of the transmission. The engine may run in fail-safe mode: The air conditioner may stop working and the radiator fans may run constantly.įor example, as per the service bulletin 05-002-12 for the 2011 Dodge Journey with the 2.4L engine, to repair the trouble codes P0117 (Engine Coolant Temperature Sensor Circuit Low) or P0118 (Engine Coolant Temperature Sensor Circuit High), the brake booster vacuum hose that was routed too close to the ECT sensor connector must be replaced. In some cars, symptoms of this problem show up as erratic readings of the temperature gauge. This causes interruptions in the signal to the PCM and the PCM sets the fault. One of the common problems is when the sensor has poor connection inside or in the connector or in the wiring harness.
#Coolant temperature sensor code#
If the signal from the sensor is missing, or it is outside of the expected range, the PCM turns on the Check Engine light and stores the related trouble code in its memory. Based on this signal, the PCM adjusts the engine performance and operates the electric radiator fans when the temperature reaches a pre-determined level. The PCM supplies a reference voltage (typically 5 Volt) and constantly monitors the ECT sensor signal. In some cases, this may help prevent overheating.Īn ECT sensor is connected to the main computer (powertrain control module or PCM). This allows the CHT sensor to measure the temperature of the engine correctly even with loss of coolant. The CHT sensor (see the photo) works the same way, but it measures the temperature of the cylinder head metal and is not immersed in coolant. Some cars use a cylinder head temperature or CHT sensor instead of, or in addition to the ECT sensor. Steps to diagnoseĮCT sensor is connected to the engine computer or PCMĪ second coolant temperature sensor could be installed in another part of the engine, or in the radiator.
#Coolant temperature sensor how to#
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