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P1407 OBD2 Fault Code in 1994 Mustang with 3.8L V6 - Diagnosis and Fixes

Model: 94 Mustang Fault Code: P1407 Posted: 2006-06-23 13:33

I recently received a P140-7 diagnostic code on my 1994 Mustang equipped with a 3.8L V6 engine, totaling 157,000 miles. This code appeared previously on a Taurus vehicle, where replacing the DPFE (Differential Pressure Feedback EGR) sensor resolved the issue. However, this time the same fix did not work. I've already inspected and cleaned the EGR valve for carbon buildup, and verified that all hoses connected to the DPFE sensor are intact with no leaks or blockages. Despite these steps, the P1407 code persists along with a constant 'Check Engine' warning light. Any additional insights from owners who have experienced this on their 1994 Mustangs? I'm particularly interested in whether the EGR valve is sticking or if there's a vacuum leak in the system.

Related fault codes
P1407
Comments (4)
Anonymous 2006-06-23 19:27

First, confirm your engine configuration—specifically the motor size and mileage. Check for an EGR valve that’s stuck open or closed, inspect the diaphragm for leaks, ensure the EGR tube is not clogged, and verify there are no holes in the hoses leading to the DPFE sensor. These are simple but effective checks that can often resolve P1407-related issues.

Anonymous 2006-06-24 12:49

My 1994 Mustang has a 3.8L V6 and is at 157,000 miles. I’ve already checked and replaced all hoses connected to the DPFE sensor and cleaned the EGR valve thoroughly for carbon deposits. The P1407 code remains active, and the 'Check Engine' light stays on continuously. Are there any other common causes or diagnostic steps that might help resolve this issue?

Anonymous 2006-06-26 15:45

Try applying vacuum to the EGR valve while the engine is running—does the vehicle stall or behave abnormally? This test can indicate whether the valve is malfunctioning.

Anonymous 2006-06-26 19:10

While applying vacuum to the EGR valve, carefully inspect whether it opens and closes properly. Confirm that the diaphragm maintains a secure seal and holds vacuum without leaking—any failure here could be directly linked to the P1407 code.