Just sharing a bit of information with you all.
Car went into limp mode with error P0486-16, egr sensor circuit B. After reading various threads on this the code seemed to point to the throttle body. New one fitted no change, into the garage it went. A map out of the egr was suggested and tried. On a road test the car started surging this was thought to be a software issue (2011/12) model year. Was told egr valve was the problem. Off I went on the glorious job of changing the egr. Car started and ran perfectly for a mile or so then the surging started then cleared but the reduced engine performance message was on the dash. A bit more head scratching by myself and checking wiring with a multi meter. I found the brown wire from the ecu to the throttle body had no continuity. Checked along the loom and found it had rubbed through on the bottom of the battery box.
Hope this helps anyone else with the same issues.

Last edited by Dieseljock on 8th Aug 2023 4:14 pm. Edited 2 times in total

Thanks for info, it's nice to have a solution posted.

Please can you alter your heading to something like

'P0486-16 EGR Sensor - SOLVED'

this will make it stand out as useful information. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 79k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Well done for finding the issue. Harness damage under the battery box does crop up from time to time.
Now you've replaced components in the air path, you'll need to have an air path calibration carried out, or performance of the intake system will be less than optimal, and the new components could fail prematurely, as the stop limits won't be correct. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.