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My car is a 2003 bmw e46 with 2.2 petrol engine. Just bought an elm 327 Bluetooth scanner and did some testing with it. Below are some graphs made with ScanMaster app. This is lambda output voltages then car was idling(engine was fully heated). Lamda output hot idle

Then I raised rpms to 2000 and got this graphs: Lamda output 2k rpms

Finaly I raised rpms to 3000: enter image description here

  • Welcome to Motor Vehicle Maintenance & Repair! Are you getting any codes? What's getting you to look at these in the first place? Have you tested the heat input/output of the cat itself? This can tell you if the cat is dead or not (and not an issue with the sensor). – Pᴀᴜʟsᴛᴇʀ2 Feb 11 at 17:07
  • Hello! I get sometimes lean codes on both banks. Didn't check cats temperature, thanks for hint. Car sometimes doesn't accelerate good under load(for example then going uphill from stop light). – Alex Feb 11 at 17:10
  • What I've looked for with cat operation is the steadiness of the output. If the cat isn't functioning and the sensor is good, the output of sensor 2 will almost mirror the output of sensor 1 from the same side. In the second set of outputs from B2S2, there is a little variation, but nothing like what you are seeing from B2S1. – Pᴀᴜʟsᴛᴇʀ2 Feb 11 at 17:13
  • Someone said that it should be staying near 0.7 V. As you see in first image, one sensor stays at 0.1V. What do you think has more probability: bad sensor or cat not working? – Alex Feb 11 at 17:17
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    Ask Schrodinger. – GdD Feb 11 at 17:24

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