P050C Cold Start Engine Coolant Temperature Performance
OBD-II Trouble Code Technical Description
Cold Start Engine Coolant Temperature Performance
What does that mean?
This generic powertrain diagnostic trouble code (DTC) typically applies to many OBD-II vehicles. That may include but is not limited to vehicles from Jeep, Jaguar, Dodge, BMW, Land Rover, Toyota, VW, Ford, Mitsubishi, Mazda, etc.
A stored a code P050C, means that the powertrain control module (PCM) has detected a problem with engine coolant temperature performance. Cold start is a term used to describe an engine drivability strategy that is implemented only when the engine is at (or below) ambient temperature.
Engine coolant temperature is monitored by the PCM using one or more engine coolant temperature sensors (ECT). The ECT sensor consists of a brass (or plastic) housing with a thermal resistor inside. The housing is designed so that it may be threaded into the engine block, cylinder head, or intake manifold; where the engine cooling passages are located. When the thermostat opens, coolant flows across the tip of the ECT sensor (where the thermal resistor is). The ECT sensor is provided a reference voltage and a ground but the sensor completes the circuit. As engine coolant temperature increases, the resistance of the thermal resistor decreases. The result of this decrease in circuit resistance is higher voltage being input to the PCM. When engine coolant temperature decreases, a reverse action occurs and circuit voltage decreases. The PCM receives these variations in circuit voltage as changes in engine coolant temperature.
Some vehicle applications utilize multiple ECT sensors. A common location for a secondary ECT sensor is in one of the radiator tanks. The PCM compares input signals between ECT sensors to determine whether or not engine coolant is flowing efficiently.
In most cases, engine coolant temperature is also compared to ambient temperature under cold start conditions. The ambient temperature sensor functions in a similar manner to the ECT sensor and is normally 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, under cold start conditions, a code P050C will be stored and a malfunction indicator lamp (MIL) may be illuminated. 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 may result in poor drivability under cold start conditions, diminished fuel efficiency, and poor heater output. A code P050C should be considered severe and rectified at your earliest convenience.
What are some of the symptoms of the code?
Symptoms of a P050C engine code may include:
Rich exhaust Cold start drivability issues No heat inside the passenger compartment ECT sensor related codesWhat are some of the common causes of the code?
Causes for this code may include:
Defective primary or secondary ECT sensor Faulty ambient temperature sensor Shorted or open circuits or connectors Bad thermostat Low engine coolantWhat are some P050C troubleshooting steps?
Diagnose and repair ECT related codes before attempting to diagnose the P050C.
Begin by making sure that the engine is full of coolant and not overheating. If it is full of coolant and not overheating, a visual inspection of ECT sensor system wiring and connectors would be my next concern.
When diagnosing a code P050C, I would gain access to a source of reliable vehicle information, an infrared thermometer with a laser pointer, a diagnostic scanner, and a digital volt/ohmmeter (DVOM).
You will need diagnostic flow charts, wiring diagrams, connector face views, connector pin-out charts, and component testing procedures and spe
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