To make several long stories very short, my car is currently running a Haltech + Osiris Tuner and I'm migrating over to a 100% Osiris setup at my tuner's recommendation. I'm aware of the technical pros and cons to both, but I'm having an issue with my OEM ECU that I need to get taken care of prior to removing the Haltech.

I have an 06 which I've confirmed to be equipped with the OEM wideband O2 sensors. I've replaced one and swapped between banks to track this issue, so I don't believe it's as simple as a dead/dying sensor.

I have constant bank 1 and bank 2 system too lean codes despite the AEM UEGO attached to my Haltech running things at 14.7 AFR. The factory widebands are reporting super-low voltage to the ECU: bank one hovers around 0.7v and bank two is usually 1.4v. I've never seen either go above 1.5v, and bank one is always much lower than two. These voltages are being monitored via the OBD port using Torque for Android.

I've been ignoring the issue and SES light due to the Haltech overriding the OEM ECU, but since I plan on removing the Haltech I would like my O2 correction to work. Clearly, it won't work as it is now. It'll just begin dumping fuel to compensate for the low voltage.

My question is: If the sensors are brand new and the voltage isn't improved, what should I be looking at? Is this a common mode of failure for the ECU itself? Are there any specific diagnostics I can do to further narrow this down?

At this point I'm pretty stumped. Any input is appreciated.

Thanks

 

I should add that the exact codes I'm getting are P0171 and P0174.

 

You know you can hook those widebands into your haltech as well and skip the UEGO. Haltech can even log those values for you and see what they are outputting.

Your other apps are receiving data over CAN through the ECU. If the ECU has blown analog inputs then you will get junk data.

 

With all the issues I was having the UEGO was to isolate the stock parts from the equation. I'll probably be selling both it and the Haltech itself in a few weeks if I can get to the bottom of this. I think I need to start tracing the O2 0-5v wire with the engine running and see what voltages I get where. In theory there should only be a few potential points of failure but you never know, especially with my luck

 

Just tried logging data while pulling the O2 sensor fuse, with interesting results. With the fuse pulled, I see 0.3v on bank one and 0.6v on bank two. I'm pretty sure I should see zero, or at least see the same voltage on both sides. Something is definitely wrong here.

 

Also getting the same low voltage with the Haltech completely removed. I think it's the ECU itself.

 

Just ordered a new ECU. Will let you know how it pans out...

 

Selling the haltech? If so PM me.

 

Well I got the new ECU installed today. Didnt help, I'm still seeing very low voltage on the sensors.

 

...I'll be damned. It wasn't the ECU, it was the phone software. The bank 1/2 sensor 1 Voltage value is wrong. I hooked the laptop up to watch the O2 values in Cipher and they were spot on, following what the Haltech was commanding.

Anyone else using Torque for Android? Can someone check this on their car?