NYBrian

Hi everyone - long time reader but first time poster - I have a repair issue and am hoping a knowledgeable Lexus mechanic or forum member can offer some advice.

My 2013 ES300h blew an oxygen sensor in December and I paid for it to be replaced at the dealer. Last week the new sensor went bad and I brought it back to the same dealer where it was replaced again (at their expense this time since it was only about 2 months so presumably still under guarantee.) On both occasions I knew what the problem was going in as I have a scanner that plugs into the port under the dash ("P013A O2 sensor slow response - rich to lean bank 1 sensor 2") - all good so far..

4 days and all of 40 miles later my car threw the same check engine code again so back to Lexus. Now they are telling me that it is the OTHER O2 sensor (i.e. sensor 1) but my code reader says it was actually sensor 2 again. They gave me a whole story on the phone that sensor 1 can trigger the sensor 2 code because it 'blocks communication with the other sensor'. This makes no sense to me - kind of like breaking your right foot and having your left foot swell up instead. Naturally they want to charge me another round of parts and labor for this which is quite expensive.

So - Are they trying to take me for a ride so they don't have to refix this a second time on their dime? Unfortunately my car is long out of warranty (150k miles) so no help there. Any expert knowledge and advice would be greatly appreciated. Thanks!

bc6152

I can't say whether the dealer is blowing smoke at you or not regarding replacement of the "other" sensor, but I do know that you can get this done much cheaper outside of the dealer and it's not a complicated fix. Find a reputable independent that you trust if Lexus won't fix it under warranty.

Eslader

One thing that isn't widely appreciated about ECU codes is that they do not generally diagnose anything. They simply point to a system that is out of spec. The ECU is telling you that the oxygen sensor is not behaving as expected, but what does that actually mean? Is the sensor bad? Did a mouse partially chew the sensor's wire which is now not transmitting the signal as it should? Is there an exhaust leak? Is the catalytic converter working properly? *All* of those can cause a P013a code, which is why a *proper* diagnosis needs to be undertaken before parts get thrown at the car.

IMO if the code was thrown by anything other than a bad oxygen sensor (which, seeing as you've replaced it already, seems likely) your dealership should be on the hook for the cost of the o2 sensor replacement as applied to the cost of whatever is actually wrong, because they should stop assuming the computer will tell them exactly what to do all the time.

Of course, it goes without saying that your dealership will disagree with me on that.

afpj

Are you able to see fuel trims and the sensor voltages? A lazy sensor one can trigger sensor two error codes. Sensor one may not be bad enough to trigger a code but if it causes the air fuel mixture to be incorrect and the catalytic converter is not burning cleanly it can trigger a downstream sensor error. Checking sensor voltages will help this diagnosis. sensor 1 should be fluctuating rapidly but sensor 2 should be a steady state. Is that the only code?