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New O2 sensor, same codes.


Well-Known Member
November 10, 2008
Reaction score
City, State
Weiser, ID
Year, Model & Trim Level
1998 Mountaineer
1130 1131 1132 all Bank 1 upstream sensor
0172 downstream sensor too lean bank 2
0175 downstream sensor too rich bank 1
on a 1998 5.0

All O2 sensors, cats, injectors, coils, cam and crank sensors, plugs, wires, timing chain and sprockets, IAC, EGR valve and pressure sensor and pipe (pipe had a crack), ECM replaced with one updated to last software, PCV valve, TPS.

All that's been changed and still those codes randomly pop up and it runs like crap. But sometimes it runs great.

It can't be the MAF because that would cause those errors for both banks. I've cleaned the MAF with special MAF cleaner.

What else can cause this?