P0152-front O2 sensor hi voltage. READY TO GIVE UP.

what about cat ECU,S, Would they cause this? Also, id confirm the previous owner didnt put aftermarket 02 sensors on

 

Just because the sensors were replaced doesn't mean they arent bad. What is the voltage right to left for the fronts. Does that read 1.49v? If so you may have a wiring issue or the sensor is bad. I believe it should be around 1 or less.

 

I know they are tough to get to but if you want to fix this issue you may have no choice. Did you try disconnecting them to see if it still reads the same voltage. If it does than its the pull up voltage you are seeing and the sensor or connection is bad.

https://www.autozone.com/repairinfo/common/repairInfoMain.jsp?targetPage=productsHowToInspect&leftNavPage=productsHowTo&pageId=%090996b43f80a01215&subtitle=test

 

I agree. That's why it could just be the sensors themselves. But You said the previous owner replaced them. I would ask myself why? Pre cat sensors usually last a long time so he may have had the same issue. Is there anything common to the pre cat o2 circuit.

 

Just curious does it smell or look like it's running rich? It may actually be an engine issue like a vacuum leak or injector problem .

 

That sounds like you replaced a lot of stuff that is in the ECU's domain. The dealer can plug the car in and reset the "computer adaptions on the ECU's". This is done when a new ECU is introduced to the system. Not sure if it will help if you have a lot of aftermarket mods but just sharing in case you want to start a dialog with a dealer tech that has the tools.

 

disconnect sensor does V go to zero?

1.4xV on bank 1 and 2 implies both running rich.

A cause can be leaky fuel injectors. When if ever were they REMOVED from car and cleaned and balanced?

 

The 1.5V showing at Key on engine off is Bias Voltage. Its what the ECM uses to check for open and shorts. You can use that voltage to check for circuit integrity and a good ECM by pulling the signal to ground and seeing if the reading goes to zero. Make sure the prior owner installed the proper O2 sensor. You can check proper operation of a Wide Band sensor by monitoring the voltage in graph form on your Scan Tool and snap throttle. The voltage should go initial lean (positive voltage) and then rich (negative voltage) as it responds to the exhaust Oxygen content. It then should go flat. Also what are your Fuel Trim values? Are they showing negative? If so, then you have a rich condition, as the ECM is trying to lean the Air/Fuel ratio.

 

Is that in open loop or closed loop warmed up. I’m guessing you already tried doing a ecm reset by disconnecting battery power for a night.

 

Well you can try what Kevin said and have the ecu's reset. Are you sure you don't have any type of vacuum leak? Did you try the propane trick up and down both sides of the engine. Who did the injectors? Was it a dealer? Could they be incorrect and dumping fuel? Do you know anyone with an emissions analyzer to see whats coming out of the tail pipes. It could be legitimately rich.

 

What are short and long term fuel trims at idle and 2500 rpm on each bank? Total fuel trim values are short plus long term as long term fuel trims goal is to keep short term fuel trim as close to zero as possible. For example, if short term trim is a constant -5% then long term fuel trim is moved to -5% by the ECM thereby raising short term trim back to 0%

 

I would look into step 2 below to do a check of the calibration resistor.

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