Husqvarna 445, 445 E and 450 E Ignition Fault Finding and Replacement

The Husqvarna 445, 445E and 450E chainsaw service and repair troubleshooting guide will help with the repair and service of the ignition. The carburetor may just need a clean, adjustment or replacing, this guide should help with this. A Service Manual detailing the ignition removal, testing, and refitting as well as more complete chainsaw repair information available to download. Also a Parts List, Operator Manual, and carburetor manual are also available to view or download as a PDF which can be read on any device or printed.

Time taken for a medium skilled person to do this is about 30 minutes to 2 hours. The repair fully Covers the following Husqvarna chainsaw models:445, 445 E and 450 E.

Ignition module – testing

Fig 7

If there is a fault in the ignition system the ignition module must be tested before the ignition system is removed.

Test the ignition module as follows:

    • Connect a test spark plug 502 71 13-01 to the ignition lead and clip the test spark plug onto the cylinder.
    • Turn the engine over using the starter cord.
    • If the test spark plug produces a spark the

ignition module is OK. (see figure 7)

Ignition module/flywheel – removal


Fig 8


Remove the cylinder cover. Disconnect the HT lead,

remove the spark plug and fit piston stop 502 54 15-

01. in its place. Take off the starter assembly, release the leads from the cable guide and remove it. (see figure 8)


Fig 9





If replacing the ignition module (B), loosen the cable lug (C) and screw (A) and unscrew it. The ignition module can be left in place if you are simply removing the flywheel. (see figure 9)


Loosen the flywheel nut (E) using a suitable socket and remove it.(see figure 10)

When replacing the cables, they are fitted on the stop switch. as shown in figure. (see figure 9)



Fig 10

Knock on the punch using a metal mallet until the flywheel releases from the shaft. Remove the punch and the flywheel. (see figure 10)

Cleaning and inspection

  • Clean all parts, especially the tapers on the

flywheel and shaft.

  • Check that the flywheel is not cracked or da- maged in any other way.

Ignition module and flywheel

Fig 11

– refitting


Fit the flywheel on the crankshaft journal. Turn the flywheel so that the key lines up with the keyway in the shaft.

Fit the nut on the shaft and tighten to a torque of

25-30 Nm. (see figure 11)



Air gap tool

Fig 12

To refit the ignition module proceed as follows:

Turn the flywheel so that the magnets are in line with the ignition module. Fit the ignition module with the plastic feeler gauge (502 51 34- 02) held in position at the same time, without tightening the bolts. Fit the earth cable (black) (A). Set a distance of 0.3 +/- 0.1 mm, between the ignition module and magnet. The measurement applies to the two lowest lugs on

the ignition module. Tighten the screws, tightening torque 4.5–6 Nm. Fit the blue cable on the ignition module. (see figure 12)


Then refit:

    • cable guide and press the leads into position
    • HT lead
    • starter assembly, tighten to a torque of 2.5–3.5 Nm
    • cylinder cover

When replacing the cables, they are fitted on the stop switch as shown in the middle figure on the previous page.

Ignition troubleshooting and service for Husqvarna 445 445e 450e chainsaws

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