Where can I locate the engine number of a Demio Year 2000?

Help in the link

https://www.google.com/search?q=mazda+demio+speed+sensor+location

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Here are some common torque settings for the Mazda Demio with the ZJ engine:

1. Cylinder head bolts - 35-40 Nm (26-30 lb-ft)
2. Main bearing bolts - 54-61 Nm (40-45 lb-ft)
3. Connecting rod bolts - 25-29 Nm (18-21 lb-ft)
4. Camshaft bearing cap bolts - 8-10 Nm (6-7 lb-ft)
5. Intake manifold bolts - 22-25 Nm (16-18 lb-ft)
6. Exhaust manifold bolts - 25-28 Nm (18-21 lb-ft)
7. Flywheel bolts - 78-85 Nm (58-63 lb-ft)

It's important to note that these torque settings may vary depending on the specific year and model of your Mazda Demio. Always refer to your vehicle's service manual for the correct torque specifications.

Check this video out. Mazda demio 1999 engine number

You need to identify the year/model and engine.
Have a look on:

http://www.troublecodes.net/mazda
https://www.engine-light-help.com/mazda-check-engine-light.html

please visit link below for information
http://www.mytimingbelt.com/Results.aspx?ModelId=192

The # on the drivers door frame can vary according to where the car was marketed but give that # to cybermonkey in tech forum or try cybermonkey.com and he will cross it and give you all the specs. hope this helps. Gene

I am not familiar with this car, but most newer cars have it located in the fuel tank. However, I hear that some Mazdas have it located under the back seat and then remove a small panel. That would be where I'd start looking. I hope this helps you.

Change oil at least every 5000 miles use 5W30W

Take off the wheel where you think the noise is coming from and check your brakes and inspect the suspension. Sounds like a brake issue.

indicates a TR sensor or a TCM problem
either of which would have been explained to you along with a quote to fix
they are only sensor problems and not a failing transmission