What does DAF fault code P3421 point to?

P3421 is reported in this data as: Cylinder 3 engine-brake solenoid control circuit/open report. It can be linked with B413 depending on truck model, engine and live diagnostic data.

Can I order a part from fault code P3421 only?

Use the fault code to narrow the diagnosis, then verify the installed OEM number, VIN, connector, actuator type and part photos before ordering or quoting.

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Fault-code lookup

DAF fault code P3421: likely components, OEM numbers and symptoms.

Cylinder 3 engine-brake solenoid control circuit/open report. This page groups every component report connected with P3421, 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 P3421.

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

Fuel / brake / bypass valve

B413 · B413 engine brake solenoid cyl 3

DAF

Cylinder 3 MX engine brake solenoid group. Intended for B413, P3421, P3423 and P3424 searches plus diagnosis of intermittent retarder complaints.

Top symptoms

Engine brake force markedly reduced
Engine brake cuts in and out on long downhill runs
DAVIE actuation test on cylinder 3 fails

OEM numbers

B413

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Defect symptoms

Symptoms reported with P3421

Engine brake force markedly reduced

Engine brake cuts in and out on long downhill runs

DAVIE actuation test on cylinder 3 fails

Warning comes after repeated brake-switch use

No drivability issue until engine brake is used

OEM numbers

OEM references to check

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

B413

Why it happens

Likely root causes behind P3421

Open circuit on ECU output or short to ground/supply.
Cylinder 3 solenoid coil failure after heat soak.
Oil contamination or varnish causes plunger sticking.
Harness fault at rocker-cover or ECU output.

Fitment

Trucks and engines that report P3421

Model	Engine	Years
XF 105	PACCAR MX Euro 3/4/5	2005-2013
XF 106	MX-11 / MX-13 Euro 6	2013-2023
CF 85	PACCAR MX Euro 4/5/6	2005-2022
CF 480 / CF 530	MX-13 Euro 6	2017-2023

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