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P0174 OBD2 Diagnostic Code in 2004 Ford Mustang Mach 1: Causes and Solutions

Model: 2004 Mach 1 Mustang Fault Code: P0174 Posted: 2015-08-23 14:10

Hello, I've been experiencing the P0174 diagnostic code for approximately one year. The issue first appeared after just 100 miles of driving during an 110-mile trip home from my purchase in November. I have already cleaned and replaced the Mass Air Flow (MAF) sensor using a dedicated intake cleaner, and I've swapped out all spark plugs and coil packs as well. The vehicle is equipped with a Ram Air Cold Air Intake and an aftermarket exhaust system. Despite these modifications, the P0174 code persists. Any accurate troubleshooting steps or recommendations would be greatly appreciated.

Related fault codes
P0174
Comments (3)
Anonymous 2015-08-23 15:43

Avoid using oiled air filters. If you currently have an oiled filter, clean the MAF sensor and replace the filter. Check for vacuum leaks—specifically in Bank 2 of the Engine Control Module (ECM). Use the old carburetor spray method to test for leaks. Also, consider whether you have access to a diagnostic scanner to monitor live data from the engine.

Anonymous 2015-08-24 02:34

I do own a diagnostic scanner and currently use an oiled air filter. However, I don- t have the original factory filter housing. Are there suitable non-oiled cold air filters that can serve as a direct replacement for my setup?

Anonymous 2015-08-24 10:34

The optimal configuration is the original Ford factory setup—off-road or modified systems may not provide consistent performance. As a practical substitute, visit a reputable parts store (such as NAPA) to find compatible non-oiled cold air filters. While there, also purchase a MAF sensor cleaner, a carburetor spray cleaner, and a fuel treatment product like Techron or Seafoam. Begin by cleaning the MAF sensor, then use your scanner to monitor live data for fuel trim (FT), oxygen sensors, and compare left versus right side readings—this may reveal imbalances. Always verify for vacuum leaks as part of the diagnostic process.