Code 643a after timing belt job

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Code 643a after timing belt job

Post by TheMrFailz »

Well I had a feeling something stupid would happen. Was driving my car around the driveway just to make sure it wouldn't explode after doing a timing belt job. Let the car idle to hot nothing bad happened until I turned the car back on a few minutes later so I could fix its parking spot. Upon turning it on I got 643a flashing and then solid. According to my maxidiag tool it's a camshaft position code for the exhaust which I'm confused about because I had it locked up in the back to the intake camshaft using a cam shaft locking tool. The only thing I can think of is that maybe I had the actual cam pulley itself set wrong or something as I didn't see any particular info on where to set it since it's a VVT cam and adjusts independantly. In this case I set the cam pulley to have it's timing mark be as close to the cover timing marks as possible.

2002 v70 2.4t, 184k miles, brand new belts.


I think I may have spotted my issue:

@~2:50 he mentions that some are spring loaded some are not (mine isn't) and that you're supposed to manually rotate them back on the non spring loaded versions whereas I, going by the mark, basically had it all the way forward.
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Post by RickHaleParker »

You do have a different VVT.

ECM-643A is a timing issue.
The control module checks that the camshaft is in the correct position in relation to the position of the crankshaft. If the position of the camshaft is incorrect, the control module will adjust the adaptation for the camshaft. Diagnostic trouble code (DTC) ECM-643A or ECM-644A is stored if the adaptation becomes too great. Most likely you did not get the VVT aligned to the camshafts.

Note! This procedure must be carried out with precision as any deviation could generate a fault symptom.

This is the tool kit:

1. Remove timing belt.
2. Align and lock down the crankshaft with the crankshaft alignment tool.
3. Align and lock down the camshafts with the camshafts alignment tool.

4. Align the VVT to the camshafts: Note! Oil the center screw before installation.

Push on the variable valve timing unit/timing gear pulley on the camshaft.
Install the center screw (1) which secures the variable valve timing unit to the camshaft. Tighten slightly.
Slacken off, but do not remove the screws (2) which secure the timing gear pulley to the variable valve timing unit.

Turn the timing gear pulley until the screws at the oval holes are in the center position. Tighten the screws (2) slightly.

Turn the variable valve timing unit clockwise to its limit position so that the unit is in its end position.
Position the upper timing cover

Undo the center screw and continue turning clockwise until the timing gear pulley marking aligns with the marking on the upper timing cover.

Tighten the center screw in the variable valve timing unit. Tighten. See: Tightening torque:Summary of specific components and tightening torques .

Variable valve timing center screw 120 Nm
Variable valve timing center plug 35 Nm

5. Install timing belt
6 Remove alignment tools.
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Post by daninater »

I think you nailed it. I'm in the exact same spot having just replaced timing belt and components and throwing a Code 643A with my 2004 S60 2.5T. During the first run up no issues, but after I restart my engine the second time I show a check engine light that reads out 643A. During replacement I lined up on my marks, used a forward camshaft locking tool purchased from Canada which locks between the teeth on the cam's and highly suspect I'm just a little bit off due to that play. Time for a redo, I'll update on here so future generations of frustrated Youtube University graduates like myself have a little less grief while saving money on their cars.

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Post by SuperHerman »

Don't get fooled by not having a CEL on the first start. You will only get an immediate code if you have a hard code, such a dead sensor. It usually takes 2-3 drive cycles for the Volvo to display timing faults.

Do as RickHaleParker suggests and redo the timing as he listed.

Regardless always turn the motor by hand a few times to make sure you don't have valve interference before trying a starter start.

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Post by abscate »

It sets on the restart after it detects a cam flank error.

I wrote this up inApril 2020,in the P80 forum, title Contains ‘cam flank Discussion‘

viewtopic.php?f=1&t=93792&p=541694&hili ... nk#p541694
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