Technical Description of OBD-II Trouble Code
The Exhaust Gas Recirculation B Control is Stuck Closed
What does that signify?
This is a generic diagnostic trouble code (DTC) for the powertrain and is applicable to OBD-II vehicles. This includes vehicles from various manufacturers such as Ford, Chevrolet / GM / Cummins, Dodge / Ram, Isuzu, Pontiac, Toyota, BMW, Mercedes, etc. Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
If your vehicle has stored the code P045F, it means that the powertrain control module (PCM) has detected an issue with the exhaust gas recirculation (EGR) valve control system.
In the case of the P045F code, the valve appears to be stuck in the closed position according to the PCM. The designation “B” refers to a specific position or stage of the step-down EGR valve control system, which is explained further below.
The EGR system is responsible for allowing the engine to consume a portion of the unburned fuel from the exhaust system. This system is necessary to reduce the levels of nitrogen oxide (NOx) emissions produced as a byproduct of gasoline and diesel engine operation.
The key component of the EGR system is an electronically controlled (EGR) valve that opens to allow exhaust gases to re-enter the engine intake. The PCM uses input signals from the throttle position sensor (TPS), vehicle speed sensor (VSS), and crankshaft position sensor (CKP) to determine the appropriate timing for opening or closing the EGR valve.
Vehicles with this code typically have a step-down EGR valve. The step-down EGR valve operates in stages based on factors such as throttle position, engine load, and vehicle speed.
In some models, the PCM also monitors the position of the EGR valve plunger. If the actual position of the EGR valve differs from the desired position commanded by the PCM, a code P045F will be stored and the malfunction indicator lamp (MIL) may illuminate. Other vehicles use data from the manifold air pressure (MAP) sensor and/or the differential pressure feedback EGR (DPFE) sensor to determine the position of the EGR valve. Most vehicles require multiple ignition cycles with a failure before the MIL illuminates.
Photo of the exhaust gas recirculation (EGR) valve:
What is the severity of this DTC?
From a drivability standpoint, the closed position of the EGR valve does not cause any serious issues. Therefore, a code P045F can be addressed at your earliest convenience.
What are some of the symptoms of the code?
Symptoms of a P045F EGR trouble code may include:
What are some of the common causes of the code?
Possible causes for the P045F code include:
What are some P045F troubleshooting steps?
To diagnose a code P045F, you will need a diagnostic scanner, digital volt/ohmmeter, and a reliable source of vehicle information.
Before diagnosing the P045F code, it is recommended to visually inspect all wiring and connectors related to the EGR system. Replace or repair any corroded or damaged components as necessary.
Next, connect the scanner to the diagnostic port and retrieve all stored codes and freeze frame data. Take note of this information, as it may be helpful if the P045F code is intermittent. Clear the codes and test drive the vehicle to see if the code is reset.
If the code is reset, reconnect the scanner and monitor the data stream. Check the desired EGR position (usually measured in percentage) and compare it to the actual EGR position displayed on the data stream. They should match almost instantly.
The DPFE and MAP sensors should indicate whether the EGR valve has opened or closed as desired. If there are any MAP sensor or DPFE sensor codes present, they may be related to the P042F code and should be addressed accordingly.
If the desired EGR position differs from the actual position, follow the manufacturer’s recommendations for testing the EGR actuator solenoids using a DVOM. Step-down EGR valves may use multiple solenoids to control the full range of EGR system operation.
If the EGR system for the specific vehicle uses a DPFE sensor, follow the manufacturer’s recommendations for testing it. Consult connector pinout charts and vehicle wiring diagrams from your vehicle information source to assist with testing. Replace any defective sensors as needed and retest the system.
The DVOM can be used to test individual circuits between the PCM connector and the EGR valve connector. Disconnect all related controllers from the circuit before conducting the tests.
