The Sad Saga of the 2007 Lexus ES350 and a P0051 AF Sensor Heater Circuit Code

by | Dec, 2021 | Electrical, feature, Toyota, TOYOTAtech Features | 2 comments

Some months ago, I was called to a shop to assist in the diagnosis of a 2007 Lexus ES350 (Figure 1) with a code P0051, “A/F Sensor Heater Control Circuit Low (B2S1)” (Figure 2). We’ll call this shop “Shop B.” Another shop, let’s call them “Shop A,” ...

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  1. Pete Moler

    Edwin, Loved the fact that you found the answer to your problem, lots of perseverance! I had a similar issue with a neighbor’s 2004 Chrysler Sebring. It was a P0134 for B1S1 heater circuit. This heater is constantly grounded, the positive side is duty cycled through the ECU. I got to look at the vehicle after the second O2 sensor and first engine ECU. I scanned the circuits involved and everything appeared to be okay when I was looking at it. Finally I got it to act up, the ground to that sensor was intermittent. Repairing the faulty ground wire finally fixed the problem.

  2. Johnny Nguyen

    Thank you so much for your post, i fixed my coworker 2007 lexus es350 same exact problem, the ground juction B32 plug was lose from ground cap, someone reinstall the engine and did not plug all the way down, Pin 46 white wire grounded to the juction B32 plug.

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