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C4 1.6 E-Hdi 2015 P0299 Turbo Underboost Fault	Please Register to enjoy additional Member Benefits

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sandman1976 United Kingdom

Fri Mar 31 2023, 03:40am

Member No: #60634

Joined: Mar 31 2023
Location: Congile

Have a 2015 Citroen C4 1.6 e-hdi with a turbo under boost fault.
Car was parked up for a few months, went to run it and it was rough, Ran it for about 70 miles next journey and it dropped an injector, replaced the 4 (as recommended) and got it coded.
Now it idles smooth and has no misfires etc.

Took it for a run and it's gutless, no "get going" power!
After a while the EML comes on and when code read it says P0299 turbo under boost although it runs ok and can get up to motorway speeds eventually.
The reader only says P0299 Turbo Underboost, it's not pointing me at anything specific.
This fault didn't exist before the injector fault, its low mileage and full comprehensive service history.

Removed and cleaned the EGR (Was actually quite clean anyway).
Removed and cleaned the EGR pipework best i could.
Removed the DPF and cleaned it off the car.
Replaced the VAC module at the front just under the turbo.
Replaced the Actuator.
No problems/splits/damage with the boost pipework and the vacuum pipes are sucking properly.

Actuator pulls in when running and moves up/down when accelerating.
The Turbo it's self spins freely.
Has turbo pressure up to the butterfly valve (top left of engine).
Butterfly valve opens/closes.

I am 3 months into this and at a loss on where to go now, i would like to verify that the EGR is actually working but no idea how to do that?

Anyone super savvy have any further ideas before i drive it off a cliff?

Thank You.

Geoagros Portugal

Sat Sep 16 2023, 05:07am

Member No: #61191

Joined: Sep 15 2023
Location: Portugal

I've got a 2006 coupé and I'm in the same place as you are. No luck on my side neither and the mechanics seem to be pretty clues too


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