Error Code P045F is defined as Exhaust Gas Recirculation B Control Stuck Closed.

This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, especially those made from 1996 up to the present. These vehicles may include (but are not limited to) Vehicle brands may include (but are not limited to) Ford, Chevrolet, GM, Cummins, Dodge, Ram, Isuzu, Pontiac, Toyota, BMW, Mercedes, etc. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

Definition

Error Code P045F means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has determined a problem in the EGR (exhaust gas recirculation) valve control system, as it appears to be stuck in closed position. Designation “B” applies to a specific position or stage of the step-down EGR valve control system.

The EGR works by allowing the engine to consume a part of the unburned fuel from the exhaust system; it’s an important system to lessen harmful NOx (Nitrogen Oxide) levels which is a byproduct of gasoline and diesel operation.

The EGR’s focal point is the electronically controlled EGR valve, which allows exhaust gas to re-enter the engine intake. The TPS (Throttle Position Sensor), VSS(Vehicle Speed Sensor), and CKP (Crankshaft Position Sensor) send input signals to the PCM, which the latter uses to determine when the conditions are right to open/close the EGR valve.

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Vehicles with this kind of system also come with a step-down EGR valve, which operates in stages according to the degree which the throttle is opened, the load of the engine, and the speed of the vehicle.

In other vehicle models, the EGR valve plunger’s position is checked by the PCM; if its desired position (as recommended by the PCM) is different from the actual position, then the Error Code P045F will be set, and the Check Engine light will be activated. Other vehicles use data contrived from MAP (manifold air pressure) sensor and DOFE (differential pressure feedback) sensor to determine whether or not the valve is in the right position. Most vehicles will require multiple ignition cycles (with a failure) before Check Engine light lights up.

Common Symptoms

Since the EGR valve is in a closed position, the vehicle will have no serious drivability and performance issues, and there may be likely no noticeable symptoms other than increased fuel consumption. Thus, the problem should be addressed at your earliest convenience.

Possible Causes

Common causes for this code include:

  • Faulty EGR valve
  • Faulty EGR control valve solenoid
  • Open or short wiring or connectors in the EGR control circuit
  • Faulty DPFE sensor
  • Bad EGR valve position sensor
  • Malfunctioning or wrong program in the PCM

How to Check

As with other error codes, diagnosing this code starts with the use of a diagnostic scanner, digital volt/ohmmeter, and a dependable vehicle information source.

Technicians usually start their diagnosis by inspecting the connectors and wirings related to the EGR system. Burned, corroded, and damaged connectors and wires must be repaired, if not replaced.

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Next step, the technician will connect the scanner to the diagnostic port to retrieve all stored codes and freeze frame data. He will take note of this data to determine whether the code is intermittent or not. The codes are then cleared, and then the vehicle will be taken for a test drive.

If the code resets, technicians will then connect the scanner and observe the data stream and the desired EGR position (typically measured in percentage) and actual EGR position as shown on the data stream display. They should be identical within a matter of milliseconds.

The MAP and DPFE sensors must show whether the EGR valve is open and closed (as desired). If there are MAP sensor or DPFE sensor codes present, then they must be related to the error code and should be treated as such.

If the desired EGR position changes from the actual position, technicians will then follow the recommendations from the manufacturer to test the EGR actuator solenoids with the DVOM. Step down EGR valves may use multiple solenoids to affect the full spectrum of EGR system operation.

If the EGR system of the vehicle uses DPFE sensor, technicians will still have to follow recommendations from the manufacturer for testing. Connector pinout charts and vehicle wiring diagrams found in your vehicle information source will aid in testing. Replace defective sensors as required and retest the system.

The DVOM can also be used to test individual circuits between the PCM connector and the EGR valve connector. All related controllers must be disconnected from the circuit before starting the diagnosis.

How to Fix

Common repairs include:

  • Repair or replacement of burned, corroded, or damaged wirings in the connectors and wirings in EGR system
  • Replacement of faulty sensors

After performing any diagnosis or repairs, the PCM must be placed into readiness mode before assuming the repairs are successful.