Technical Description of OBD-II Trouble Code
The exhaust pressure control valve A is stuck in the open position.
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) that applies to OBD-II vehicles equipped with exhaust pressure control valves. This includes vehicles from various manufacturers such as Dodge, Honda, Chevy, Ford, VW, etc. The specific repair steps may vary depending on the year, make, model, and powertrain configuration.
A stored code P047F indicates a malfunction in one of the exhaust pressure control valves. The “A” designation typically refers to the bank of the engine that contains the #1 cylinder, although this can vary between manufacturers. In this case, the valve is stuck in the open position.
Exhaust pressure control valves are used in turbocharged gasoline and diesel engines. They operate similarly to throttle bodies, using an electronically controlled plate to restrict exhaust flow as determined by the PCM. There may also be a position sensor and/or a pressure sensor associated with the exhaust pressure control valve.
Increased exhaust back pressure is used to raise the engine and engine coolant temperature more quickly, which can be beneficial in very cold climates.
This is a basic overview of exhaust pressure valve operation. It is important to check the specifications for the specific vehicle before making any assumptions. When the PCM detects a cold air intake temperature below a minimum threshold, it activates the exhaust pressure control valve and maintains its operation until the intake air temperature normalizes. The exhaust pressure control valve is designed to remain in the wide open position when deactivated by the PCM.
If the PCM detects that the exhaust pressure regulator is not in the desired position, or if the exhaust pressure sensor indicates an out-of-position condition, a code P047F will be stored and the malfunction indicator lamp (MIL) may illuminate.
What is the severity of this DTC?
Since exhaust back pressure can affect climate control and drivability functions, it is important to address a stored code P047F with a certain degree of urgency.
What are some of the symptoms of the code?
Symptoms of a P047F trouble code may include:
What are some of the common causes of the code?
Causes for this P047F code may include:
What are some P047F troubleshooting steps?
To diagnose a code P047F, a reliable vehicle information source is required. Other tools needed include:
After visually inspecting the system’s wiring and connectors, locate the vehicle diagnostic port. Connect the scanner to the port and retrieve all stored codes and freeze frame data. Record this information as it may be helpful during the diagnosis process.
Next, clear the codes and test drive the vehicle to see if the P047F code immediately returns. If there are intake air temperature codes or engine coolant temperature codes present, address and repair those issues before attempting to diagnose the P047F.
Search for technical service bulletins (TSB) that apply to the specific vehicle, codes, and symptoms in question. If a matching TSB is found, it can greatly aid in the diagnosis.
If scanner data display is not available, the infrared thermometer can be used to measure the actual exhaust temperature. This can help determine if the exhaust pressure control valve is functioning correctly and detect if the valve is stuck in either the open or closed position.
