Technical Description of OBD-II Trouble Code
Performance Issue with Cold Start Engine Coolant Temperature
What does that signify?
This generic powertrain diagnostic trouble code (DTC) is applicable to various OBD-II vehicles, including but not limited to Jeep, Jaguar, Dodge, BMW, Land Rover, Toyota, VW, Ford, Mitsubishi, Mazda, etc.
A stored code P050C indicates a problem with the engine coolant temperature performance, as detected by the powertrain control module (PCM). Cold start refers to an engine drivability strategy that is implemented when the engine is at or below ambient temperature.
The PCM monitors the engine coolant temperature using one or more engine coolant temperature sensors (ECT). The ECT sensor is housed in brass or plastic and contains a thermal resistor. It is threaded into the engine block, cylinder head, or intake manifold, where the engine cooling passages are located. As coolant flows across the tip of the ECT sensor, the resistance of the thermal resistor decreases with increasing temperature. This decrease in resistance results in higher voltage being input to the PCM. The PCM interprets these voltage variations as changes in engine coolant temperature.
Some vehicles may have multiple ECT sensors, with a common location for a secondary sensor being in one of the radiator tanks. The PCM compares input signals from the ECT sensors to determine the efficiency of engine coolant flow.
Under cold start conditions, engine coolant temperature is often compared to ambient temperature. The ambient temperature sensor functions similarly to the ECT sensor and is usually located near the grille.
If the PCM detects a discrepancy between the ECT sensors and/or the ambient temperature sensor that exceeds the maximum threshold during cold start conditions, it will store a code P050C and may illuminate the malfunction indicator lamp (MIL). Multiple ignition cycles with a failure may be required for MIL illumination.
Cold car:
What is the severity of this DTC?
A lack of engine coolant efficiency under cold start conditions can result in poor drivability, diminished fuel efficiency, and inadequate heater output. It is important to address a code P050C promptly.
What are some of the symptoms of the code?
Symptoms of a P050C engine code may include:
What are some of the common causes of the code?
Possible causes for this code include:
What are some P050C troubleshooting steps?
Prioritize diagnosing and repairing ECT related codes before attempting to diagnose the P050C code.
Start by ensuring that the engine has sufficient coolant and is not overheating. If the coolant level is adequate and there are no signs of overheating, inspect the wiring and connectors of the ECT sensor system visually.
When diagnosing a code P050C, it is recommended to have access to reliable vehicle information, an infrared thermometer with a laser pointer, a diagnostic scanner, and a digital volt/ohmmeter (DVOM).
Accurate diagnosis of a code P050C requires diagnostic flow charts, wiring diagrams, connector face views, connector pin-out charts, and component testing procedures and specifications. This information can be found in your source of vehicle information.
Connect the scanner to the vehicle diagnostic port. Retrieve all stored codes and freeze frame data, and record them for reference. Clear the codes and test-drive the vehicle to see if the code is reset.
If the P050F code is immediately reset, turn the key on with the engine off (KOEO) and reconnect the scanner. Use the infrared thermometer to measure the actual coolant temperature near the ECT sensors. Compare the ECT data displayed on the scanner with the actual coolant temperature. If there is a discrepancy, follow the diagnostic steps below.
If the scanner displays an abnormal ECT value (e.g., -38 degrees):
You can use the DVOM to test individual coolant and ambient air sensors according to the manufacturer’s specifications and testing procedures. Sensors that do not meet the specifications should be considered faulty.
