1998 Ford Ranger what do these codes mean in layman terms

CORTO

MEMBER
1998 FORD RANGER
6 CYL
2WD
AUTOMATIC
112,000 MILES

Hi there, and thanks a lot for the work.
My truck has been running rough and I did all kinds of things, including new catalytic converter, both 02 sensors replaces, MAS cleaned and regular tune up. Now it runs better but still not perfect and with check engline light on giving me 3 codes: p0155, p1151, p1152. The last two ones seem to contradict each other. I am not a mechanic, and cannot figure out what the h02s21 switch is that seems to be missing. In basic terms, what am I looking for?
Thanks a bunch

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

PO155 - HO2s21 = heated oxygen sensor bank 2 sensor 1

That means that the 1st onygen sensor which is heated, is bad on bank 2 which is for cylenders 2, 4, 6

The PO1151 and 52 are related. One is for a lean mixture (not enough fuel) and one is for a rich mixture (too much fuel). Since this is before the catylatic converter, my first thoughts would be a bad sensor (O2 sensor), a random vacuum leak, in need of a tune up (which you did) or a leaky fuel injector.

Check for vacuum leaks first, If you can't find anything, perform a fuel pressure test to see if there is a leak down problem (system doesn't hold pressure when key is first shut) which could indicate a leaking injector.

Let me know what you find or if you have other questions.

Joe