bgoetz

I am having a heck of a time getting rid of a secondary O2 CEL. Last year when driving to have a test pipe and VAFC Neo tune I drove through a massive puddle which caused my CEL to come on for the secondary O2. After the test pipe was installed with a defouler and a tune it came back. So now I was in a situation where I had no clue if it was the TP or fried O2. I replaced the O2 and the CEL cam back. I finally just got around to putting in a smaller defouler (the med size in the kit), CEL came back. So I guess my next step is the smallest size defouler, although at this point I fully expect the CEL to return. Anyone have any other thoughts? Is there anything else that the h2o may have damaged that could cause this?

flanders

Are you getting the same code and which one is it?

Mike RT4

As Flanders has said, you need to read the code, as the CEL light will come on if there is too LITTLE flow as well as too MUCH flow.

If it has the been triggered by the former. then moving it further out or restricting the flow to the sensor will not stop the light coming on, in fact it will make it come on sooner or more often.

Never blindly clear the code....

King Tut

Why not stop wasting time and money and purchase a solution that can simply disable the rear O2 sensor? The O2 connectors should be water tight. Exactly what CEL are you getting?

bgoetz

Everytime they have been 136, 137, and 157. I am assuming they are the same codes this time, but will pull them to be sure.

bgoetz

So from reading those are not common test pipe/o2 related codes. Seems more likely that something may have shorted when I drove through the puddle? Apparently the ACG runs the same circuit so I checked that fuse and it is good. Anyone know more about the Secondary 02 heater circuit and what I may have damaged by running through the water initially?

bgoetz

Ok, so tossed in the smallest defouler and still the same codes. At this point I have ruled out all common things other than maybe the O2 that I bought being bad?..

This started when I ran through a massive puddle and I think it just happened to be the same day that I went to a test pipe. Does anyone have any ideas?

I have also read about a wiring fix with a resistor, does anyone have a link to this? I want this code gone!!

Mike RT4

The CEL codes you are getting would seem point to a faulty sensor / wiring, or that the restrictor is too small / moved too far from the flow.

Remove the restrictor and place the O² sensor directly in the test pipe, in theory (if the sensor is good), you should then be getting code 420 (which is when the O² sensors are reading ranges with not a big enough disparity (due to the removal of the cat).

P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0137 6 - 3 P0136 ____ Secondary Heated Oxygen Sensor Circuit Low Voltage (Sensor 2)
P0157 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)

If it still comes up with the same codes, then the next step would be to change the sensor.

Micalbertl

^Fully agree

Many people talk as though the 420 cel is hard to get rid of it honestly isn't. Since you drove through a puddle I would say you shorted a sensor and if the new one you bought shows that it is good after following Mike's instructions check all your wiring. It is meant to be waterproof but if there were any tiny breaks in the wire's shielding it could get damaged. I hope its just your O2 sensor. Good luck

Chuck S

Put the OEM cat back in the car and drive it a week. If the MIL is still on the sensor/wiring is bad. If the light goes out you need a cat or better "defouler."

-- Chuck