Disconnected O2 sensor. No Codes??
Thread Starter
Heel & Toe
Joined: Sep 2001
Posts: 21
Likes: 1
From: Rayville LA
Disconnected O2 sensor. No Codes??
I installed a new O2 sensor in the L98 this morning hoping to fix my not so great gas mileage. When it didn't help at all, I tried disconnecting it, and to my surprise, it didn't set off any codes. Do I have a problem?
The old pigtail had been melted a bit by the precat (actually the precat inadvertently got replaced by a regular cat) but it was mostly on the sensor side, which is now replaced. Could this have caused some problems?
The old pigtail had been melted a bit by the precat (actually the precat inadvertently got replaced by a regular cat) but it was mostly on the sensor side, which is now replaced. Could this have caused some problems?
Melting Slicks
Joined: Dec 1999
Posts: 2,816
Likes: 2
From: Austin, TX
Re: Disconnected O2 sensor. No Codes?? (hotclayb1)
After you disconnected it and started the car, did you drive around at all to make sure it warmed up? When you first start the car, it will stay in 'open loop' mode for a while until coolant temp gets up and the O2 sensor gets up to temp (specifics depend on the year of the car). If you started it and shut it off right away, it probably wouldn't have set a code. If you did drive it around for a while and it still didn't set a code, then I'm stumpped!
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Disconnected O2 sensor. No Codes?? (hotclayb1)
Even if the engine is warm it can take a set amount of time to go closed loop. In any case the car should go closed loop within 5 minutes maximum. If it doesn't set a code you might double check that your computer is even going into closed loop mode. If it's not that could be some of your trouble.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Disconnected O2 sensor. No Codes?? (hotclayb1)
It should give a 13. If using a scanner, you can check loop status; otherwise ground the DLC and if the check engine light is flashing on & off about 2x's/second, it's still in open loop. When it slows down, it's in closed loop. With the car running; O2 connected, DLC grounded, closed loop detected, light will be on if the O2 signal is rich/off if it's lean; ie, reading the O2 signal. If none of this works, disconnect the TPS - you should get an immediate 22. If not, the ECM is probably bad.
