mathslope

My 2005 ES330 is showing a P0051 code (Bank 2 Sensor 1 O2 Sensor). Turns out there's a technical service bulletin out of it, which recommends replacing both Bank 1 and 2, Sensor 1, and flashing the ECU. I've attached the TSB. Now my first car, my dependable daily driver, has 204k miles, wayyy outside the 80k warranty repair. The two dealers I took it to wouldn't touch it without a $155+tax diagnostic fee, on top of the repair. I confirmed my VIN is before the production effective change, below is how I decoded the VIN.

I try to do all my own repairs. Recently I changed the water pump, respective belts, thermostat, brakes, and Bank 1 O2 Sensor 2. I could replace the sensors but what about flashing the ECU? Would changing the sensors not solve the problem?

Coincidentally, now my headlights turn on everytime I start the car, regardless of how sunny it is. When I turn the headlights to off, and back to auto, the headlights work fine. Just turn on everytime I start the car. I don't really believe in coincidences..... could these problems be linked?

For the cherry on top, while my car was sitting off, but headlights still on, in the dealer's drive-in bay for ~10min, they had to jump the car to get it to start. I've never had to jump my battery before, not even almost. Been a clean start every time.

Not sure what my next move should be, would appreciate advice or tips



How to decode VIN, how to confirm production effective change CIN.

LeX2K

If that was my car I'd try to find an independent mechanic to do it, one that tends to work on these cars. This is something I couldn't do myself don't have the tools/software but it's possible to DIY this fix. Or how about finding a used ECU with the updated part number and get it virginized so you can program new keys.

You probably just need a new battery, also your alternator might not be doing the job.

mathslope

Do you think it's foolish to change only change the offending sensor and hope for the best?

Arsenii

Hello,

Try measuring the resistance of the A/F sensor heater circuit (two Black wires), if that's good, there is probably no point of replacing the sensor. Check if you have 12V and Ground coming to the heater element, if not, check all the fuses, Heater (A/F HTR) Relay and wiring. If none of that will help, it is probably the ECU at fault.

Hope this helps and best of luck!

Oro

Exactly, make sure the battery and alternator are sound before chasing down other electrical issues. Atlernators pretty much can let go any time above 150k/15 years. Or much sooner if German.