Codes 538 and 172

WYNRYPEN

MEMBER
1953 FORD ESCORT

Hey !
95 ford escort.

it starts up, then runs for a good 4 minutes, then stalls, I got two codes from my scanner which are 172 and 538:

:arrow: : 172: lack of heated oxygen sensor (h20s-1) switches, indicates lean bank #1
538: which is insufficient rpm change,

what in the hell is 172 saying? :X

here are the things I have done:

1)changed the air filter
2)changed the fuel filter
3)changed the fuel pump
4)changed the o2 sensor
5)changed out with a used MAS
6)changed out with a used IAC (both from pick n pull)
8)new gaskets in all the necesary parts

1 Reply

BACKYARDMECHANIC

MECHANIC
337 POSTS

I happen to have the same car 1.9 and have had the same problem. The code 172 heated 02 sensor means the car is running lean but I can see where one would suspect the O2 sensor. The insufficient rpm change could be you didn't run the test right and there is nothing else wrong. I'am assume you still have the check engine light on even AFTER changing the listed parts. Have you cleared the code after making the repairs? You may have already fix the problem and not know it. I fix the problem by cleaning the fuel system/ injectors and it has fix the problem. The car is running leanning but it may be because of a mechanical malfunction ( clogged injectors) not a electronic one. Try cleaning the injectors ( the one you put in the tank will work but cleaning the system with the pressure type is better )and let me know how you make out. Hope this helps Backyardmechanic :)