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Fault-code lookup

DAF fault code P0234: likely components, OEM numbers and symptoms.

Overboost condition or stuck wastegate / control problem. This page groups every component report connected with P0234, so a mechanic can move from the error code to the relevant OEM numbers, defect symptoms and fitment checks.

A fault code alone is not a parts order. Confirm with live data, VIN, installed OEM number, connector and part photos before quoting or fitting.

Likely components

Component families linked with P0234.

The same code can appear with different root causes. Use the OEM number and symptom pattern to choose the right branch.

Turbocharger Service offered · unit verification required

4033084H · HY35W turbo for LF / ISBe 5.9

Holset

HY35W wastegated turbo group for DAF LF and CF with Cummins ISBe 5.9L engines. Failure patterns are mainly shaft play, oil starvation and sticky wastegates.

Top symptoms
  • Lazy boost rise and smoke between shifts
  • Loss of power and slow turbo spool
  • Excessive black smoke under acceleration
OEM numbers
4033084H 4033084 1405848 4025227 4025227NX 4025227RX 4892550 3592655
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Turbocharger Service offered · unit verification required

4033174H · HX35W turbo for LF / ISBe6 6.7

Holset

HX35W turbo group for DAF LF with Cummins ISBe6 6.7L engines. The repeated reports focus on bearing and seal failure, oil in charge pipes and underboost on motorway grades.

Top symptoms
  • Black smoke under throttle from underboost
  • Loss of power on motorway grades
  • Whistling or screaming noise that builds with revs
OEM numbers
4033174H 4033174 1409886 4955172 4955172N 4955172NX 4955172RX 4039503
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Fuel / brake / bypass valve Diagnostic information only

B368 · B368 bypass valve

DAF / PACCAR

B368 bypass valve data is reported in several ways: fuel bypass, wastegate/bypass valve and EGR cooler bypass actuator. The lookup page should therefore make the ambiguity visible and route users by fault code and symptom.

Top symptoms
  • Reduced motor power and lazy spool-up
  • Truck smokes more on hard acceleration
  • Boost comes and goes instead of building cleanly
OEM numbers
B368 1693005 1740032 1740033
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Defect symptoms

Symptoms reported with P0234

Lazy boost rise and smoke between shifts
Loss of power and slow turbo spool
Excessive black smoke under acceleration
Blue smoke at idle from compressor-side oil leak
Whining or siren noise from worn bearings
Truck struggles to hold speed on small gradients
Black smoke under throttle from underboost
Loss of power on motorway grades
Whistling or screaming noise that builds with revs
Oil-soaked intercooler hoses and blue smoke
Turbo shaft endplay excessive on inspection
Intermittent underboost after long climbs
OEM numbers

OEM references to check

Use these links when the workshop note only contains an OE number instead of the exact part family.

4033084H 4033084 1405848 4025227 4025227NX 4025227RX 4892550 3592655 3592654 3595654 3596647 1399432 1731668 1819794 1399431 1745674 1819795 1819796 1731669 4033174H 4033174 1409886 4955172 4955172N 4955172NX 4955172RX 4039503 4039504 4028404 4042735 4043245 3531038 3531038H 3531696 3531810 3531810H 3532210 3802233 3802233RX 3802391 3802391RX 466575-0001
Why it happens

Likely root causes behind P0234

  • Oil feed starvation scores journal bearings and shaft surfaces.
  • Hot shutdowns coke oil in the centre housing.
  • Wastegate actuator diaphragm rupture or pivot seizure after heat cycling.
  • Compressor wheel rub after excessive shaft play.
  • Wastegate sticking from carbon build-up around the exhaust housing.
  • Journal bearing wear and shaft endplay at high mileage.
  • Oil seal failure pulls oil into the intercooler and charge hoses.
  • Overspeed from boost leaks or sticky wastegate capsule.
Fitment

Trucks and engines that report P0234

Model Engine Years
LF 45 Cummins ISBe 5.9L Euro 3/4/5 2001-2012
LF 55 Cummins ISBe 5.9L Euro 3/4/5 2001-2012
CF 65 Cummins ISBe 5.9L Euro 4/5 2001-2012
LF 55 Cummins ISBe6 6.7L Euro 4/5 2005-2013
LF 45 Cummins ISBe 6.7L Euro 4/5 2006-2013
XF 105 MX-13 Euro 4/5 2006-2013
CF 85 MX-13 Euro 4/5 2006-2013
XF 106 MX-11 / MX-13 Euro 6 2013-2023
CF 480 / CF 530 MX-13 Euro 6 2017-2023

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