Read the link below. I believe the knocking sound we experience is similar to this:

https://www.facebook.com/ToyotaMalaysia/pos...1?stream_ref=10

For my case, I had just complained to the SA during my first service last week. But the problem could not be replicated during a short test drive with the SA - I just discovered now that the bumps near the Service Center (which is in an industrial area) were wider and smoother, hence no knocking were heard when going over the bumps. The SA also said they found nothing wrong with the car suspension or absorber during the service and inspection. But the problem still persists now whenever I drive over bumps. So I wrote an email to 'customersupport@toyota.com.my' that same day to voice my frustration about the knocking sound. Surprise, surprise - a few days later, the Frontline Executive from the same SC called me up to fix an appointment just to diagnose the problem with their 'most experienced' technician. I have been driving around the SC and identified several 'suitable' bumps in a housing estate nearby that are narrower and able to reproduce the knocking sound. Will update here after the troubleshooting appointment next week . I hope UMW is not hiding something they know just to save cost even though they keep on assuring me not to worry and that they will replace any defective parts if found. Let's wait and see.

This post has been edited by hairybelly: Apr 15 2014, 05:31 PM

If I remember correctly, there was no knocking sound when I first got the car. It's something that appeared over time. And not all types bumps will produce the knocking sound. Hopefully yours is from a newer batch that had been rectified.

Update: Just got back from the SC today. Went for test drive with the foreman and managed to replicate the knocking 'kruk' sound when going over bumps. I also complained about thin roof very noisy during heavy rain. Outcome is - they believe the front lower arm is the culprit for the knocking sound. They will order the front lower arm for the knocking sound and also 'roof silencer' for the noisy roof (I believe this must be some insulation material). Once the parts arrive, they will arrange for appointment, but I would need to leave the car there for 1-2 days to fix these 2 issues..... Hopefully they know what they are doing...

Not sure if they can definitely solve the issues, at least they are trying. FOC of course. My SC is in Melaka.

Strange that they will order the lower arm for me, but did not mention anything about engine mounting. Maybe my knocking sound is different from yours? Or maybe they have engine mounts in their stock and will replace both lower arm and engine mount for my case, I am not sure. Anyway, hope they get it right the first time as I don't want to go there too many times for the same issue.

Yup, the rear fog lights can be very irritating at night in normal driving conditions. I experienced it the other night when I was following this new Vios at my taman. I believe it's a lady driver, as I have seen this particular car a few times before. The red lights were really bright that I got fed up and switched on my front fog lights. She didn't seem to get the message - or maybe she couldn't be bothered by my puny stock Vios front fog lights.

Actually I believe all the SCs have been informed of these issues. In my service report, they quoted a particular Toyota service bulletin number as a reference to my knocking sound complaint. Maybe the difficulty is, there could be there many types of knocking sounds and each has got its own different solution. Now it's up to the experience of the foreman or staff to identify which type of knocking sound I am facing during the test drive, referring back to their many service bulletins on different types of knocking sounds. That's why I was surprised they suggested the problem was lower arm instead of engine mounting for my complaint.

Ask them to insulate the roof noise as well.

The thin roof on the new Vios is really an oversight by Toyota designers. Seriously, our tropical region has some of the heaviest rainfall in the world...

Well, at least they are willing to rectify the mistake. Kudos.

Yup, they will only recall if it's life-threatening. Otherwise, replace only when people complain.
But I hope they have put in the insulation for the newer batches. Those planning to book, make sure they have done this.

Am I the only one with lower arm defect instead of engine mounting, causing the knocking sound? I am only worried they misdiagnosed the problem and order the wrong solution for me. Btw, I took delivery of my car at end of February.

It might take some time as the roof insulation part is made in Japan and currently there is a major shortage. Even my SA couldn't give a firm timeline when the part will arrive.

@drakzero
The knocking sound over hump will get worse after some time if it's not resolved, trust me. Just pray that Toyota has rectified the problem in their new batch. Otherwise, you will have to make appointment with SC to get it fixed later.

Mine is loud even at slow speeds when going over hump or uneven road surface - with the music on as well. SC tested it and said they need to change the front lower arm, although majority of the other complainants were told it's the engine mounting problem. Maybe my knocking sound is different from the others. Will do the replacement together with roof silencer when the parts arrive.

Got my car back 5 days ago. Supposed to change only the lower arm suspensions (1 pair), but was surprised they also replaced the insulator sub assy 1230521440. So far so good. Need to monitor further.
But roof insulation has not arrived yet.

They diagnosed the problem of knocking sound to be caused by the front lower arm suspension when I went to complain. No mention of engine mount during that time. When I got back my car, the service report shows both lower arms and engine mount 440 have been replaced. Even the SA pointed to me the new engine mount. I suspect maybe they still hear knocking sound after changing lower arm, so they could have proceeded to replace the engine mount. Just my guess.

SC is in Melaka. My friend's Vios was also diagnosed here, but was only prescribed engine mounting. He will send in his car in a few weeks time.

You'll be fine with 10,000 km.

Mine is so far so good after almost 1 month. Changed engine mount 440 and lower arm assy since 12 July.

Not in Klang Valley. Approximately 130km south.