Contour Enthusiasts Group Archives Forums General Troubleshooting Replaced Oxy sensor, things aren't good since.

Well, yesterday I replaced the bank 1 oxygen sensor (wasn't as bad as I thought it would be), and reset the computer, I think. The "how tos" say to remove fuses 4 and 11 for at least 10 minutes, I did. Fuse number 4 is for the DRL's, why remove that one? Anyway, I decided to take the car for a decent drive of 25 miles and visit a bro of mine. The car ran like crap, idle-wise. The first 5 miles the CEL did not come on, then it was on for the next 7, then off the rest of the way. Before the O2 change it would intermittently go off and on whenever. Left my brother's and the light didn't come on for 12 miles, then stayed on the rest of the way home. Didn't use the car again until this evening. Started it up and it died, started it up and it died, started it up and put my foot on the gas to keep it idling. Went to town to get a pizza (4 miles) car ran OK. Got pizza went home, came to a stop sign and car was surging. Got home and got my code reader. Here are the results: KOEO 172-Lack of heated oxygen sensor switches (HO2S-1), indicates lean bank 1. 176 Lack of heated oxygen sensor switches (HO2S-1) indicates lean bank 2. 332 Insufficient EGR flow detected. I also got a code 335 but forgot to look at the reason for it. KOER: 172 same as KOEO. 136 Lack of heated oxygen sensor (HO2S-2)during KOER indicates lean bank 2. 332same as KOEO. 538 Invalid cylinder balance test due to throttle movement during test. 536 BOO circut failure. 653 TCS did not change states during KOER. I got the code definitions from my '95 Ford service manual CD.

I know the sensor is in tight and that the plug is in good , so I am puzzled as to the results. Especially because now bank 2 is apparently acting up also. And before the change my codes were 172 and 173, which are just for the bank 1 sensor.

Any ideas??

Later. Pepse.

Fuse 4 is also for ignition.

As for the lean codes, you have a massive vacuum leak. I would suggest looking for a broken hose or crack in a housing somewhere. Should hear a hissing sound (or ticking sound). You may have to use carb cleaner to spray around gaskets, clamps and hoses if a visual inspection doesn't locate the problem.

In addition, for the EGR codes, test the EGR (vacuum/suck test), clean the throttle body and check/change the DPFE.


TB cleaning
TB cleaning thread

EGR vacuum test.
Modified test for EGR (per Ray and Steve):
(remove the green vacuum hose from the top, be careful as it is brittle, and apply a vacuum (attached a small hose and suck on itl) to see if the car stumbles while running. This indicates a properly operating EGR.

Does it work properly?

NO: The EGR valve is defective or the EGR passages are clogged. Check (and clean, if needed) the passages behind the Throttle Body. Purchase a TB gasket, and remove the air plenum (rubber accordion tube) then remove the TB. Clean the EGR passage (small cut-out in the outer edge of the TB's mating surface) really well, install a new gasket and re-attach the TB. If the passages are clear, the EGR valve is defective. While rare, they do fail.

YES: The EGR valve works and the passages are clear. The likely fault is the DPFE sensor or its sample hoses, followed by the EVR solenoid or the PCM. May also be caused by interconnecting vacuum lines or electrical connections.

DPFE test from Autozone

Did you pull the fuses from the fuse panel under the hood?

Tony, I haven't noticed a leak, but then I will spray around and hear what may happen. As for the surging idle I had a leak earlier this year and had to replace the big hose that the PCV sits in. After that everything was good, until I took the car in for the 12K tranny fluid replacement from when the tranny was rebuilt last year. When I got it back the idle was kinda crappy, but not this bad. And I am sure if I asked the place I took to they wouldn't be guilty of anything unusual. Like when the tranny was rebuilt they knocked off, and lost, my right side DOHC badge; they said it wasn't there when it came in. And I can't quite see what I could have bumped whilst changing the oxy sensor. Altho I suppose there might be some kinda air line in that area where I worked on it.

I cleaned the TB last fall. Being that I have had that EGR code since last year I did buy a gasket, so I will have to try the test, and possibly clean it out. The DPFE? I will follow that link when I finish this reply and see what it is all about.

Jim, yeah I pulled the fuses from the under hood box.

Later. Pepse.