Hello Scotty, It's me again with the Toyota Avalon. I changed the two upstream 02 sensors, and I…

Randy

Hello Scotty,

It's me again with the Toyota Avalon. I changed the two upstream 02 sensors, and I changed the spark plugs to insure everything is firing good and not going to put carbon all over the new 02 sensors. I cleared the fault and also disconnected the battery to make sure everything was cleared. Started the engine, and D@&* it! ! ! After only 20 seconds the check engine light comes on with the same PO135 & PO155 heater circuit fault.
A buddy of mine told me his son had a fault cleared once and the same thing occurred to him. He was told to drive it for about 50 miles and it will reset. My son is going to take it to work tomorrow and Friday (it's 24 miles one way). If it doesn't clear, I'm at a total loss, and I don't know what to do.
Any ideas what I should check now?

Comments (4)
No. 1-4
Randy
Randy

Thank you for the information Mark. Oy? You're making my head spin again. Conflicting information overload. The hardest part for a DIY redneck who is intelligent and capable but on an extremely tight budget is getting accurate facts. Two thing in common with local garage and dealerships in my area is they all want to work on your car for you, and neither of them are helpful for information. The only differences between local garage and dealerships in my area is one of them wants to have your first born child when you make payment. Can you guess which one, lol? Filtering through information is very challenging sometimes, such as in this case, as it's new territory for me. I've been under the impression if the CAT was blocked the engine wouldn't run smooth, and it would smoke and smell. Currently, the engine runs smooth and there's no noticeable smoke or odor at all from the exhaust. Is this information accurate?

Mark Whinton
Mark Whinton

A plugged / faulty catalytic converter can also cause this issue -

ScottyKilmer
ScottyKilmer

pray it's the temp sensor, cause it could be the wiring too.

Randy
Randy

Got one more thing I think I can check. I found some information that explains that the 02 sensors work with the engine coolant temperature sensor. If the engine coolant temp is sending the wrong signal and saying the engine is hot, when it's not, this could cause the faults to occur.

The purpose of codes P0135 and P0155 is to track the amount of time the Oxygen Sensor takes to go from indicating the fuel control system is in open loop to rapidly switching above and below the 450 millivolt set point, thus indicating the fuel control system is in closed loop. This time measurement begins after the Engine Coolant Temperature Sensor indicates the engine has warmed up sufficiently. If the signal lingers or is set below the lean-to-rich cross-count point—generally around 450 millivolts for an Oxygen Sensor—then the code P0135 or P0155 is triggered.

I wish I had found this information first, it's only $22 for the coolant temp. sensor, vs. the $350 worth of sensors I put in already. Ugh. I'll get it tomorrow and let you know if it does the trick.

You know anyone who wants to buy two slightly used 02 sensors? lol (both 02 sensors for $200)