2016 XE 2.0d — P0299 & P226C after turbo rebuild — still underboost on highway
 

Hi everyone,
I’m having an ongoing issue with my 2016 Jaguar XE 2.0d (diesel). After a turbo rebuild (removed, bench-tested by a third-party specialist, and reinstalled with adaptation), I’m still getting fault codes P0299 and P226C under certain driving conditions.
Symptoms are:

• Underboost/slow boost response on smooth highway cruising ~80–120 km/h at relatively low RPMs, especially with cruise control enabled.
  
• Occasional “reduced engine power” message and Check Engine lamp.
  
• In city driving the car behaves normally.
  
• Codes clear after restart and sometimes disappear for a day or two.
  

What has been done so far by the shop:

• Turbo removed and bench-tested — “all OK in factory settings”.
  
• DPF/soot filter checked.
  
• EGR cleaned — still no change in symptoms.
  

It feels like the turbo isn’t delivering as it should in real-world conditions, but bench test doesn’t show issues. I understand that highway boost behavior can be different from bench diagnostics.
Has anyone seen similar behaviour after a turbo rebuild on an XE diesel? How did you identify the cause and fix it? Any advice on what to check or how to interpret this would be really appreciated.
Thanks in advance!

Not sure if you have already an ingenium diesel, but earlier 2.2D (by PSA/Ford since y2000) had same issues when there were leak inside of vacuum operated actuator controlling turbo variable vane lever. Worked without issues on city / traffic, but on highway when boost had time to build up >5-10min it light an MIL and entered on restricted performane due incorrect boost value. Next start up all were Ok again.
Adding the winter conditions and water inside the actuator, what froze and melt again by engine temp, made very difficult to pinpoint this issue back then. All different codes were pushed, high/low boost or incorrect air meter / pressure values.

All the best for you in Kiev. Stay safe.
Slava Ukrajini!

Thank you so much! Your words really means a lot for me! Heroyam Slava!

+1

. . . and from "down under" on the opposite end of the world . . . we offer our support for solving your issues of boost and bullies!

Cheers and best wishes,
:icon_beerchug:

**Update:**
Got a second opinion from another Jaguar/LR specialist yesterday. They scanned the car and confirmed the same codes (**P0299 and P226C**).
During inspection we found that the actuator installed during the turbo rebuild was a cheap aftermarket (Chinese) unit. The mechanic suspected it might not be controlling the VGT position accurately under steady load.
They removed it and installed a used **original OEM actuator** to test this theory. Everything was adapted and the car now drives normally.
The plan is to drive it for a few days and specifically test the conditions where the fault usually appears: steady highway driving at about **80–120 km/h with low RPM**, often when using cruise control.
If the problem disappears, it would likely confirm that the aftermarket actuator was the cause.
I’ll report back once I have more highway miles and see how it behaves.

Update: We tried replacing the actuator with a used original one (the rebuilt turbo had a Chinese aftermarket actuator installed before). Unfortunately it did not change anything. After about 10 km on the highway using cruise control, the same problem appeared again. At this point the local specialists are suggesting that the next step may be installing a new original turbo.
I will update the thread once there is more progress.

Final update (I hope)
The issue is now fully resolved. Replacing the turbo with a brand new original OEM unit completely fixed the problem.
After installation and adaptation, the car performs normally in all conditions, including steady highway driving with cruise control. No more underboost, no fault codes (P0299 / P226C), and no reduced power messages.
So in my case, despite the rebuild and all previous checks, the root cause was the turbo itself. Only a new genuine unit solved it.
Hope this helps someone in a similar situation.

interesting 🧐
I just replaced the turbo on my 2.0d and finding a JLR branded turbo was actually rather difficult. these JLR turbos are Mitsubishi manufactured but of course jaguar has their name cast into it all over the place. I ended up getting a Mitsubishi OEM from Mitsubishi, The same one manufactured for JLR. even those are starting to disappear because Mitsubishi pulled out of China recently. yes a lot of stuff on our cars is manufactured in China. apparently the metallurgy on the shaft and turbines in these Chinese Mitsubishi turbos isn't necessarily of any quality, even if it's the JLR Version. The metallurgy in China is very poor and the machining is hit and miss. apparently it's better to put a cartridge in your original turbo from a third-party manufacturer that uses high quality components that don't have the same failure rates.
FYI: don't forget to smoke test the intake system after replacement. there is one hose and one EGR coupling that tend to leak boost.