# EMU Classic LSU 4.2 wideband not valid **URL:** \ **Category:** EMU BLACK / CLASSIC\ **Created:** [August 30, 2026, 7:01am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408 "2026-08-30T07:01:46Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![1gferrer](https://dub1.discourse-cdn.com/flex013/user_avatar/community.ecumaster.com/1gferrer/32/6610_2.png) [@1gferrer](https://community.ecumaster.com/u/1gferrer)\ **Post date:** [August 30, 2026, 7:01am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/1 "2026-08-30T07:01:46Z")
Hi everyone, I am currently troubleshooting the built-in wideband Lambda input on my EMU Classic. I have attached a screenshot of the log showing the issue. There is no specific Lambda fault code. The `Check engine code` value remains at **0 throughout the entire log**. However, the Lambda system never provides a valid reading. These are the relevant values from the log: - `Lambda is valid`: **0 throughout the entire log** - `Lambda 1`: fixed at **1.000** - `AFR`: fixed at **14.7** - `WBO is calibrating`: **0** - `WBO sensor temperature`: **0 for practically the entire log** - `WBO Heater DC`: reaches up to **85%** and runs at approximately **66% while the engine is running** - `WBO VS`: approximately **4.82 V** - `WBO IP ADC`: approximately **4.8 to 4.9 V** - `WBO RI`: approximately **2.49** - `Lambda guard status`: normally **7** ![image](https://europe1.discourse-cdn.com/flex013/uploads/ecumaster/original/2X/d/de04def2782d10504786ff4e80bb0db8e1413e5b.png) The ECU appears to be controlling the sensor heater, but it never considers the Lambda signal valid. Therefore, the fixed Lambda value of 1.000 and AFR value of 14.7 do not appear to be actual measurements. Sensor is a BOSCH 0 258 007 351 btw Thanks ---
**Author:** ![Alfa105TS](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Alfa105TS](https://community.ecumaster.com/u/Alfa105TS)\ **Post date:** [August 30, 2026, 5:33pm UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/2 "2026-08-30T17:33:27Z")
A few people have had issues with direct connection of LSU4.2 sensors to their Classics and never resolved them (me included). We’ve resorted to using external WBO controllers. @Jadzwin_ECUMASTER - do you have any suggestions? Example of one of my logs for comparison. ![LSU4.2 log](https://europe1.discourse-cdn.com/flex013/uploads/ecumaster/original/2X/8/8908065d7fe6bae56352a6f64bb99477e7fee404.jpeg) ---
**Author:** ![matth](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@matth](https://community.ecumaster.com/u/matth)\ **Post date:** [August 31, 2026, 11:17pm UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/3 "2026-08-31T23:17:24Z")
If you’re not getting a temperature, you probably have a bad connection. I had the same, I repinned the plug and no issues since ---
**Author:** ![Alfa105TS](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Alfa105TS](https://community.ecumaster.com/u/Alfa105TS)\ **Post date:** [September 6, 2026, 9:46am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/4 "2026-09-06T09:46:54Z")
Not connection issues for me. You can see the voltages being recorded. I recently shifted onto the v3 software which has different setup for the LSU4.2. I’ve tried connecting an LSU4.2, on both the old v1 classic software and v3Studio. No joy on either of my Ecumaster Classics, using two different genuine Bosch LSU4.2 sensors. Back to using external controllers. ---
**Author:** ![matth](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@matth](https://community.ecumaster.com/u/matth)\ **Post date:** [September 6, 2026, 9:59am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/5 "2026-09-06T09:59:49Z")
Yes, same with my issue, I had all the right voltages, but heater dc sat at 65% which seems to be a fail safe value, and intermittent temperature, because of poor connection on the heater pins ---
**Author:** ![Alfa105TS](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Alfa105TS](https://community.ecumaster.com/u/Alfa105TS)\ **Post date:** [September 8, 2026, 10:31am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/6 "2026-09-08T10:31:20Z")
Yes, thanks Matth - I understand your issue and the fix that worked for you, but my Heater DC is cycling fine, not flat lining. I’ve rewired it several times, even tried one of the ecumaster cables, no joy. Anyway, I’m back on the external controller, which is fine - just a bit more signal delay to deal with. ---
**Author:** ![matth](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@matth](https://community.ecumaster.com/u/matth)\ **Post date:** [September 8, 2026, 11:52am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/7 "2026-09-08T11:52:17Z")
So your WBO temperature isn’t 0 as stated in your original post? ---
**Author:** ![Alfa105TS](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Alfa105TS](https://community.ecumaster.com/u/Alfa105TS)\ **Post date:** [September 8, 2026, 11:41pm UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/8 "2026-09-08T23:41:08Z")
That was 1gferrer’s post. ---
**Author:** ![matth](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@matth](https://community.ecumaster.com/u/matth)\ **Post date:** [September 9, 2026, 6:28am UTC](https://community.ecumaster.com/t/emu-classic-lsu-4-2-wideband-not-valid/6408/9 "2026-09-09T06:28:59Z")
Ahh sorry, I missed that. Either way, my point is valid for OP