What does code p0442 on a Ford Expedition mean?

P0442 code on a Ford Expedition, or any OBD-II compliant vehicle, means that the Exhaust Gas Recirculation (EGR) System has detected a malfunction in its operation. The EGR system routes a controlled amount of exhaust gas back into the engine's intake manifold to reduce the formation of nitrogen oxides (NOx) emissions. When the P0442 code is set, it indicates that the EGR system has detected a problem with the flow of exhaust gas or that the EGR valve is not functioning properly.

The P0442 code can be caused by several factors, including:

- A faulty or stuck open EGR valve

- Faulty EGR valve position sensor

- Clogged or damaged EGR passages or tubes

- Faulty EGR vacuum solenoid

Symptoms of a P0442 code may include:

- Illuminated check engine light

- Rough idling

- Stalling

- Reduced engine power

- Increased emissions

To diagnose the P0442 code, a qualified technician will typically perform the following steps:

- Inspect the EGR valve and related components for damage or obstructions

- Test the EGR valve for proper operation using a scan tool

- Check for vacuum leaks in the EGR system

- Test the EGR vacuum solenoid for proper operation

- Replace any faulty components as necessary

If the P0442 code is not addressed, it can lead to further problems with the vehicle's emissions and performance. It is important to have the code diagnosed and repaired by a qualified technician as soon as possible.