2020 Corolla 2.0 Hybrid TS droning noise at 1500 rpm

[Lucash312]

Hi dear Toyota owners.
I would appreciate it if someone could help me to identify the source of the problem.
I have a 2020 Toyota Corolla Hybrid TS  2.0. After 10-15 minutes from the start of the trip, a droning noise appears in the rear exhaust area. This only happens when the engine is at 1500 rpm and under load. When the exhaust is cold, or engine is not loaded,  everything is fine.
On my complaint, the dealer replaced the rear part of the exhaust system 3 month ago. But the problem reappeared now, when the warranty is ended. To be honest, the noise now is much quieter that before, but still annoying. Especially when the car is going uphill. 
Please respond, who encountered similar issue.

 

[fourbanks]

The warranty is for 10 years, I believe if you have had the service carried out by your dealer? 

[TonyHSD]

Hi, 

very likely you have exhaust bracket broken again or exhaust heat shilled broken. Perhaps back to the dealer and ask for investigation and warranty repair. If not and you gonna do it yourself then you will need to go under the car and ask someone to rev the engine at these certain rpm so you can find the exact part that needs fixing. Typical Toyota problem. 

[Lucash312]

5 hours ago, fourbanks said:

The warranty is for 10 years, I believe if you have had the service carried out by your dealer? 

Perhaps you meant a 10-year warranty on through corrosion. My booklet says 3 years warranty and 5 years for a hybrid system. Possibly I missed something. Service was carried out by the dealer

[fourbanks]

13 minutes ago, Lucash312 said:

Perhaps you meant a 10-year warranty on through corrosion. My booklet says 3 years warranty and 5 years for a hybrid system. Possibly I missed something. Service was carried out by the dealer

The car has a 10-year warranty if carried out by your dealer each year. The service give you a one-year added warranty 

 

Up to 10 years / 100,000 mile Toyota warranty*

Every new Toyota comes with a 3 year manufacturer warranty followed by a 12 months / 10,000 miles additional warranty, with every qualifying service*. Up to 10 years or 100,000 miles, whichever comes first, letting you relax in the knowledge that you and your vehicle are in safe hands. 

[Lucash312]

5 hours ago, TonyHSD said:

Hi, 

very likely you have exhaust bracket broken again or exhaust heat shilled broken. Perhaps back to the dealer and ask for investigation and warranty repair. If not and you gonna do it yourself then you will need to go under the car and ask someone to rev the engine at these certain rpm so you can find the exact part that needs fixing. Typical Toyota problem. 

Hi, thanks for replying. The questions is how to rev an engine on hybrid under load? I tried maintenance mode, but couldn't repeat an issue with idling.

[TonyHSD]

11 hours ago, Lucash312 said:

Hi, thanks for replying. The questions is how to rev an engine on hybrid under load? I tried maintenance mode, but couldn't repeat an issue with idling.

Hi, 

Maintenance mode or just step on the accelerator while the car is in P and the engine should fire up and more you press the rpm will rise, also there is a slight delay when pressing and rpm rising, It doesn’t feel national but works and you can rise to high rpm. Perhaps good to check the plastic trays under the car too, because your sounds a bit softer than metallic rattling, it’s more like plastic or rubbery rattling, something like that. Check also the engine bay plastics.  
Good luck 

[Lucash312]

19 hours ago, fourbanks said:

The car has a 10-year warranty if carried out by your dealer each year. The service give you a one-year added warranty 

 

Up to 10 years / 100,000 mile Toyota warranty*

Every new Toyota comes with a 3 year manufacturer warranty followed by a 12 months / 10,000 miles additional warranty, with every qualifying service*. Up to 10 years or 100,000 miles, whichever comes first, letting you relax in the knowledge that you and your vehicle are in safe hands. 

Hi, thanks for the info. It looks like RELAX program, which automatically turns on after three years of general warranty as you mentioned. Unfortunatelly, I figured out that program unavailable in Czech where I live. Local toyota dealers are not connected to it. That's sad. But I bough car in Germany where the program works. May be I can do something with that.

[Lucash312]

8 hours ago, TonyHSD said:

Hi, 

Maintenance mode or just step on the accelerator while the car is in P and the engine should fire up and more you press the rpm will rise, also there is a slight delay when pressing and rpm rising, It doesn’t feel national but works and you can rise to high rpm. Perhaps good to check the plastic trays under the car too, because your sounds a bit softer than metallic rattling, it’s more like plastic or rubbery rattling, something like that. Check also the engine bay plastics.  
Good luck 

Hi,
You're right, that sound is not metallic. I'll try to check things you mentioned. Thanks a lot for advice.

[YarisHybrid2016]

Almost certain that's simply vibration from a part. I'd check the engine cover first (if it has one).

[AisinW]

On 6/27/2023 at 10:06 PM, Lucash312 said:

Perhaps you meant a 10-year warranty on through corrosion. My booklet says 3 years warranty and 5 years for a hybrid system. Possibly I missed something. Service was carried out by the dealer

Yes you are absolutely right. Everything is 3 years as long as you fo scheduled maintenance (oil, filters, and brake fluid) in any VAT mechanics.  The 5 years hybrid systems including ECU are default too. No need for dealership maintenance for those warranty.  Just regular oil changes.  The hybrid systems need nothing to be valid. So, you do not need Hybridsystem-Check in the first 5 years but always a good thing to clean the HV air filter annually. 

After 5th year, you still can have 15 years hybrid Battery warranty by performing Hybridsystem-Check yearly for about £50. 

I think your rattling is a loose bolts, hanger, heat shields, or clamps/joint in  of the exhaust system. Very clear it is from the piping area.

 

[Lucash312]

Hi guys, thanks for replies. I really appreciate it.

I managed to get my car on the ramp and check whole exhaust system, heat shield and plastic covers. Everything is gripping tight, no loose, no vibrations all bolt and clips are tight. The same situation is under the hood. Te problem is that I couldn't reproduce that specific sound being on ramp. Running on target RPMs on maintenance mode or parking mode didn't get any results. 
Driving with my friend as a driver, I figured out additional details. The sound only appears on specific conditions - D or R,  1500 RPM and the engine is going on tension, like when going uphill or starting from stop line. The sound goes from the front right part of the cabin. Some where the passenger feet is located (left rudder). The sound can't be heard from the outside. Only from the cabin. 

I came up with an idea, what if that sound have another origin? Might is go form defected engine mounts or something like that? Any ideas regarding that, guys?  How I can check engine mounts on a hybrid? 
Thanks in advance

[TonyHSD]

16 hours ago, Lucash312 said:

Hi guys, thanks for replies. I really appreciate it.

I managed to get my car on the ramp and check whole exhaust system, heat shield and plastic covers. Everything is gripping tight, no loose, no vibrations all bolt and clips are tight. The same situation is under the hood. Te problem is that I couldn't reproduce that specific sound being on ramp. Running on target RPMs on maintenance mode or parking mode didn't get any results. 
Driving with my friend as a driver, I figured out additional details. The sound only appears on specific conditions - D or R,  1500 RPM and the engine is going on tension, like when going uphill or starting from stop line. The sound goes from the front right part of the cabin. Some where the passenger feet is located (left rudder). The sound can't be heard from the outside. Only from the cabin. 

I came up with an idea, what if that sound have another origin? Might is go form defected engine mounts or something like that? Any ideas regarding that, guys?  How I can check engine mounts on a hybrid? 
Thanks in advance

Hi, 

engine mounts yes it is possible to be defective or broken.
To check those you will need a help from your friend. 
Let him seat in the car and start in ready mode or maintenance mode and make the engines running and you can use a long screw driver as stethoscope touch each mount with metal end and place your 👂 on the handle, make sure there is nothing that rotates nearby and can catch your screwdriver. On the part that is directly connected to the engine you should be able to hear vibrations and grinding noises but on the other metal part that is connected to the car body you should not hear those, this means the rubber works well and insulation is good. 
Next check is with the car in ready mode and parking brake applied ask your friend to select D and try to move forward, look how much the engine is moving, then select R and try to move again and look for excess play or metal clunking. 
These are good engine and transmission mounts tests. 

But before you go on all of these tests check again inside the car , dashboard, below glovebox  there are some plastic panels that are very flimsy fitted, very likely they cause that noises. 
This is from Auris but Corolla likely to be similar. 

[Lucash312]

2 hours ago, TonyHSD said:

Hi, 

engine mounts yes it is possible to be defective or broken.
To check those you will need a help from your friend. 
Let him seat in the car and start in ready mode or maintenance mode and make the engines running and you can use a long screw driver as stethoscope touch each mount with metal end and place your 👂 on the handle, make sure there is nothing that rotates nearby and can catch your screwdriver. On the part that is directly connected to the engine you should be able to hear vibrations and grinding noises but on the other metal part that is connected to the car body you should not hear those, this means the rubber works well and insulation is good. 
Next check is with the car in ready mode and parking brake applied ask your friend to select D and try to move forward, look how much the engine is moving, then select R and try to move again and look for excess play or metal clunking. 
These are good engine and transmission mounts tests. 

But before you go on all of these tests check again inside the car , dashboard, below glovebox  there are some plastic panels that are very flimsy fitted, very likely they cause that noises. 
This is from Auris but Corolla likely to be similar. 
 

Hi,
Thanks a lot for the detailed instructions! Seems like I can handle it. I will surely report on results. 

[TonyHSD]

1 hour ago, Lucash312 said:

Hi,
Thanks a lot for the detailed instructions! Seems like I can handle it. I will surely report on results. 

You are welcome. 

[Cristian r]

Hi all. I have the same issue, dealer in Germany also replaced the back box exhaust and it was ok for couple weeks, then appeared again. Was there a solution at all for your problem?

[Lucash312]

On 2/12/2024 at 9:12 AM, Cristian r said:

Hi all. I have the same issue, dealer in Germany also replaced the back box exhaust and it was ok for couple weeks, then appeared again. Was there a solution at all for your problem?

Hi! Replacement of back box didn't work to me. Having ruled out all possible options, I finally come to a conclusion, that sound comes from middle part of exhaust system. Technical guys form dealership have the same opinion after making their tests. The problem is that this part is expensive. (1500 EUR)  I don't have enough motivation to buy it yet.
Hope this helps.

[Cristian r]

Hi, thanks for the reply. I have also went back to the dealer and they said that the noise is coming from the 2 heat shields that go towards to exhaust manifold. These heat shields have some sort of kevlar type material where the bolts are connecting them to the main exhaust. They said that these kevlar connections are broken/loose, and that’s what making the noise, as they say. Problem is that they need to drop the front axle assembly to be able to replace these parts, thing that I am not soo keen about. What would you guys do?

work is done under warranty, but somehow I wouldn’t want then to mess about with the subframe..

in your case, if they wish to replace the middle part, is so expensive because that is the part with the catalytic converter ( the part that is notorious for being stolen).

 

it was suggested to me by to use exhaust paste around the bolts that hold the heat shields (temporarily of course) and see if that will make the noise disappear. The idea is to limit the movement of the heat shields, as they are designed to slightly move.

 

best of luck. Will you posted.