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1998 Ford Expedition XLT P1405 P0303 P0304 P0307 P0171 - Misfire and EVAP Code Diagnosis & Low-Cost Fixes

Model: 1998 Ford Expedition XLT Fault Code: P0171 Posted: 2014-07-02 18:55

1998 Ford Expedition XLT with V8 5.4L engine, 237,160 km. I purchased this truck at an auction and noticed it hesitates and struggles to accelerate during driving. After reaching over 100 km/h, a loud popping sound occurred followed by increased engine noise. I took the vehicle to a mechanic who reported these diagnostic trouble codes: P1405, P0303, P0304, P0307, and P0171. I'm unfamiliar with what these codes mean and am concerned about repair costs. Can someone explain the meaning of each code and whether there are affordable solutions available? Thank you.

Related fault codes

P0171P0303P0304P1405

Comments (3)

Anonymous 2014-07-03 07:07

The symptoms suggest a possible exhaust restriction in either the catalytic converter or muffler, which may have caused the loud pop and subsequent noise. Additionally, Bank 1 (passenger side of engine) is running lean (P0171). Check for vacuum leaks, including the PCV system and intake manifold gaskets. Cylinders #3, #4, and #7 are misfiring (P0303, P0304, P0-307), which could be due to vacuum leaks or exhaust restrictions—other potential causes include faulty spark plugs or fuel delivery issues. The P1405 code indicates an EVAP system issue; a smoke test is recommended to diagnose and resolve this problem.

Anonymous 2014-07-09 19:11

I replaced all the spark plugs, but was advised against installing a catalytic converter—instead, it might be better to bypass it since the vehicle is older. Is this a valid recommendation for my 1998 Ford Expedition XLT? What are the risks or benefits of doing so?

Anonymous 2014-07-10 07:29

It's advisable to consult your state’s DMV regarding emissions compliance and whether bypassing components like the catalytic converter affects registration or legal requirements.