P0154 code help

[Ackattack]

A little background first: I recently changed my clutch, and in the process I had to remove the headers. I replaced the drivers side 02 sensor because a bare wire was showing from rubbing on the frame. The pass. side O2 sensor looked fine and had no issues. I'm also not running cats but still have the rest of the emission hooked up (AIR pump)......this is on a 99 Corvette.

So now I'm finished with that and I'm driving the car. I keep setting a P0154 DTC. Besides the check engine light, the fuel mileage is down about 25%. Also, I can hear what sounds like the AIR pump running constantly. The light will come on about 5-10 minutes after I've been driving. If I clear it, it will come back on the next time I drive the car.

I don't know if the AIR pump running constantly is causing the P0154 or if the code is causing the AIR pump to run.

I did some monitoring with HPtuner last night:

So bank 2 02 sensor is pretty much constant at around 450mV, which according to the manual would be a problem..."inactivity" or something to that effect.

However, Bank 1 is cycling between 0 and ~500mV (don't remember for sure...but diffenatly down to 0) Also, the Bank 1 LTFT is maxed out at 25 (If I turn it to closed loop) if I reset the LTFT and turn on closed loop it quickly goes back to 25. It also starts missing and running poorly in closed loop. The bank 1 injectors also begin to increase in duty cycle.

So I'm thinking my gas mileage is down because its not going into closed loop mode and because the computer is adding a bunch of fuel.

I checked the wires connected to the 02 sensors and all looked well.

I was just reading on here about a 02 sensore heater fuse, I haven't gotten a chance to check that, but where is it at? Under the hood?

Anyone got some more ideas or more checks to do?

[EC_Tune]

Heater fuse sounds like one of the culprits.
Make sure your AIR tubes & gaskets don't leak or that will throw things off a lot.

[Ackattack]

I'll look at the fuse tonight and I think I'll remove the AIR system so it won't leak.

[Country Boy]

If the AIR pump is running 100% of the time it will cause a problem as its pumping fresh air right into the exhuast system and to the O2s. Itll drive the O2s crazy since theyll see the wrong mixture.

[Ackattack]

Well the O2 fuse was blown. I changed it, and it blew again.

What I'm thinking now is that when I was installing the clutch, I accidently pinched some wires in between the bellhousing and torque tube and may have messed up some wires.

So now I get the joy of trying to fix that.....hope that's the problem.

[Ackattack]

Well I think I've found the source of the problem. The new o2 sensor was rubbing on the frame just like the old one (even though it was smaller) and I'm assuming it was grounding out the circuit, causing the o2 fuse to blow.

So I removed the header and I'm working on putting in a new O2 sensor bung. Hope that solves it.

[Ackattack]

Hey thanks guys for help leading me the right direction. It was in fact the O2 sensor grounding itself on the frame. The new o2 bung is in the perfect place now, the fuse did not blow, and now both the 02 sensors are working (cycling) as normal.

It is interesting that I was getting the error code for the 02 sensor for the passenger side, but it was the driver side 02 sensor that was rubbing the frame, but they're both part of the same circuit I guess.

Now maybe I can move on to doing a little tuning instead of diagnostic/trouble shooting!