- Insufficient EGR Flow Detected:
This code is triggered when the Engine Control Module (ECM) detects that the actual flow of exhaust gas through the EGR system is insufficient.
- Faulty EGR Valve:
The EGR valve controls the flow of exhaust gas into the intake manifold. If the EGR valve is faulty or stuck closed, it can cause insufficient EGR flow and trigger code P0402.
- Vacuum Leaks:
The EGR system relies on vacuum to operate the EGR valve. Leaks in the vacuum hoses or lines can cause the EGR valve to not open properly, leading to insufficient EGR flow.
- Faulty EGR Sensor:
The EGR system uses a sensor to monitor the position of the EGR valve and the amount of exhaust gas flow. If the EGR sensor is faulty, it can send incorrect signals to the ECM, causing the code to be set.
- Faulty ECM:
In rare cases, a faulty ECM can cause the P0402 code to be set even though there is no actual issue with the EGR system.
To diagnose the exact cause of code P0402 on your 1997 Ford Explorer, you will need to perform further tests and inspections of the EGR system. This may involve checking for proper vacuum, testing the EGR valve, and examining the EGR sensor and its wiring. If you are not comfortable performing these tests yourself, it's best to consult a qualified mechanic or technician to diagnose and repair the issue.
