Geralt

My understanding is that air-fuel ratio and lambda are the same thing expressed differently. AFR of 14.7:1 is the same as saying Lambda = 1. The sensor upstream of the cat allows the engine ECU to adjust the fuel mass to the current incoming air mass. The downstream sensor is there to measure the performance of the cat. Both sensors measure oxygen. The engine will run happily without the downstream sensor (in principle) because it is not used to adjust fuel mass, only for diagnosis purposes.

Usually by the brake pedal.

The long answer is here: I got this one in the end: https://www.tayna.co.uk/car-batteries/japanese/s4020/ Make sure you check which terminal size you have.

There's at least two interfaces on the J1962 (https://www.dashlogic.com/docs/technical/obdii_connector_pinout) connector that support OBD comms: A) OBD-on-CAN pins 6 and 14. B) OBD-on-K-Line on pin 7. B is A's predecessor and has a much lower baud rate. On my 2002 2.4L only B is supported and the same is possibly true of your 2004 vehicle. If so, it's likely the workshops you speak to only have equipment that supports A. Anyway, I can recommend the following cable and software kit: https://www.ebay.co.uk/itm/124808047632

That's good value. Mine arrived from Part Souq yesterday and took just under a week for ~£16. I paid extra for quicker delivery. To be fair to the local Toyota dealer, they only wanted a pound more but they couldn't get hold of it till October.

Have you got the key for it? If not, is there a possibility that you could accidentally lock it? If so, I would remove it asap.

It most likely aftermarket. It's just another anti-theft device like a steering wheel lock.

You're welcome. You also need MVCI cable. I bought this one which comes the Techstream software and some decent support from the seller: https://www.ebay.co.uk/itm/124808047632 Alternatively you can run a virtual machine version which doesn't need installation. This is the method described here: https://forum.ih8mud.com/threads/how-to-techstream-in-5-minutes.1034923/ I found this to work just as well as the installed version.

In any case, my JOBD scanner only reads Check Engine codes. As Picasso says, to read non-emssions codes like traction control faults, you may need Techstream running on a laptop. It's not difficult but if you don't like computers, you might need assistance.

You may need a JOBD scanner. E.g. Ancel JP700. My 2003 Alphard won't speak to my OBD2 scanner that I use for my beemer so I had to buy the Ancel as well.

It's a problem indeed. I think we can help you to get the right part numbers but delivery could be more expensive. My advice is to call your local garages and ask them if they are prepared to work on Japanese imports in principle, should it go wrong. They should be able to do the mechanical bits without much problem but they will need wiring diagrams if you have electrical problems. I believe these are easier to get hold of for a Gen 2 Alphard. 2008+.

Have you tried completely disconnecting the battery for 15 mins and reconnecting, full charged of course?

Driver's side, just above the parking brake.

To run diagnostic tests and if you have a laptop then you can use Techstream with an Mini VCI cable. This is the one I bought https://www.ebay.co.uk/itm/124808047632. The suport from the seller was quite good. I doubt there are any trim values stored in NVM which would impact your problem. If I'm right, a basic reset (of the Keep Alive Memory) can be achieved by disconnecting the battery for 15 mins.

If you have a 2.4 then there’s no timing belt to change.