wowwitsgau

Last night I reinstalled my stock cat/secondary o2 sensor in preparation for smog, then flashed my car back to stock (I have an 09 AP2) using FlashPro. This morning I took it to get it smogged but they said the sensors weren't ready yet, and told me to drive the car for a bit first (makes sense since I barely drove the car in between last night and this morning). However, after driving it around for 30 min or so, I got a CEL so I pulled the code and it was a P0134 - 02 Sensor Circuit No Activity Detected (Bank I Sensor 1).

This doesn't really make sense to me as it sounds like the car is complaining about my primary o2 sensor, which I didnt modify/touch (http://www.obd-codes.com/p0134). I will go back under the car to check all the connections but I just wanted to see if anyone might have any insight as to why this could have happened. Thanks in advance

wowwitsgau

bump

Chuck S

Disconnect the battery (negative wire) for a while, then reconnect, enter your radio code, and drive around for a week. You may be getting "not ready for testing" codes that will go away in a week.

-- Chuck

wowwitsgau

Can you elaborate on what you mean by "not ready for testing" codes? Is there not a specific code that would show this instead of mine? (it sounds like p0134 is something specific)

If I disconnect the battery and reconnect, is the code supposed to go away and not come back? Or does it still stay on then might disappear on it's own later during the week

Chuck S

Disconnecting the battery should reset the ECU and erase any trouble codes. After you re-connect it it will relearn stuff and reacquire any existing trouble codes in a few days of driving. It also sets some sort of "ready for testing" code after that time. Probably so we can't just reset the ECU and run out for testing before the trouble codes come back!

Different vehicle but I disconnected the battery in my Expedition a couple of months ago (to clean it externally) and took it the next day for smog testing. Self-service kiosk computer connected to the OBD2 port rejected the car as "not ready for testing" or something similar. Did some cursory research and learned what's in the last paragraph. Took it back a couple of days later and it tested fine. I think the ECU and ignition need to cycle so many times. It's a black box to me.

Something to try. Not sure how long the battery needs to be disconnected but someone will chime in here no doubt.

I ran the S2000 thru this kiosk when the car was new-to-me and stock in July 2014 and again this July with the K&N intake, Berk High Flow Cat and either the Invidia Q300 or Tanabe Medalion Touring exhaust (I forget which). Passed smog testing both times.

-- Chuck

B serious

A CEL doesn't come on for "not ready" parameters. Or your CEL would show every single code available every time you unplug/plug in the battery or reset the ECU in another way.

Whenever the ECU is reset, it will need time to complete all its testing parameters. This could take a few days, depending on driving habits.

What "not ready" means is that the ECU still has to complete its run through a certain set of parameters after re-setting. It will monitor all emissions controls over a set amount of time/drive cycles/etc.

If all components pass the ECU's tests over time, it will show "ready" and will show no CEL's. If a component fails during this testing, the CEL will turn on, regardless if other components have completed their test cycles or not.

A O2 non activity CEL will turn on as soon as the ECU detects it. Its not one of those CEL's that the ECU will delay.

An example of a delayed CEL is the evaporative emissions CEL you get when you leave the gas cap loose.

Immediate CELs are usually set if the ECU detects a short or open circuit in an emissions component. Unplugging your O2 sensor will set an immediate CEL, for example...whether the car is in readiness mode or not, open loop or closed loop, running or not running.

Maybe a wire got moved around when you were replacing the stock stuff. Maybe it melted through and shorted on the exhaust.

Check the wiring under the car and check the fuse that relates to O2 sensor function.

Or maybe there was some sort of electronic hiccup and the light is intermittent.

Try re-setting the ECU. Does the light pop back on right away?

wowwitsgau

Thanks guys - I reset the ECU by disconnecting the battery for 30 min or so (the CEL disappeared) then drove around, but the CEL came back on. I took a look under the car and it looks like the primary o2 sensor is extremely close to the transmission, and there are rubbing marks on the transmission where it hit the wires from the o2 sensor. I'm assuming this is caused my sensor to fail.

Now the question is, why is there so much play in my exhaust? I'm running a Buddy Club header, stock cat at the moment (but Hytech 3" test pipe) and HKS 75mm exhaust and I can move the entire exhaust including the header side to side, such that the o2 sensor hits the transmission. Is something loose? Motor mounts need replacing? I have an 09 with 83000 miles and it is my track/weekend car

B serious

Is something broken or loose? Trace where all the movement is coming from.

wowwitsgau

It seems like the header I have has the o2 sensor pointing towards the transmission and is hitting it... this very likely could be the cause of the problem

A few days ago the CEL turned off on its own, then turned back on yesterday. Now it's throwing a P2252 (AFS - Line Low Voltage) as the only DTC. So weird