I have an engine damaged in a way it would be cheaper to change it rather than to mend it.

The current engine model code is2SZFEand is emitting 136g of CO² per Km.
Following the yellow jaket (« gillets jaune ») fuel tax protests, the French government announced a grant increase to 4000€ in our vehicle scrappage scheme for peoples buying a used car emitting less than 122g per Km which in our free market will only rise the value of such cars instead of helping the target peoples of course.

So since the engine needs to be changed anyway, I’m interested in changing for a less powerful gasoline engine which would emit less than the required limit.
While there are Europeans Toyota Yaris manufactured in 2007 that do emit less than 122g of CO² per Km, I’m unsure if it is technically possible to use a1NRFEor a1KRFE for example.

By compatible, I mean I want to avoid spending more than 50€ for changing incompatible parts which might (I dunno) include the gearbox or the ecu.

Update :

I went to ask for a1KRFE.
But if you want to change the engine of your car in France, you are required to ask for the manufacturer permission (or authorities will refuse homologation). I thought I could debunk usual claims for their refusal by choosing a less powerfull engine.
But it appears they still chose the answer that give them hope you’ll be forced to change your car for buying a new one from them (as usual).

So the answer is no even if the raised safety issues are spurious (such as the the exageration of homologation costs or the claim the brakes wouldn’t be powerfull enough compared to power of the new engine even if the previous and first engine is more powerfull).

  • Welcome to Motor Vehicle Maintenance & Repair! Where are you getting the "136g of CO² per KM" figure from for the 2SZFE engine? Is this something the French government puts out for the engine or is it an actual reading taken from the engine in the vehicle? Commented Nov 26, 2018 at 16:21
  • @Pᴀᴜʟsᴛᴇʀ2 It’s a number of the V7 field on the European Union Vehicle registration certificate. Since I need to change the engine, I’m good for paying the huge homologation cost anyway. Any engine model below 1200cc or created after 2006 should be below the official limit. Commented Nov 26, 2018 at 16:32
  • I'd make sure that you are able to re-register the car once the lower emissions engine has been fitted and are still eligible for the subsidy. Commented Nov 28, 2018 at 15:23
  • This story raises so many questions... This is for the resale value of the car and not for recurring road taxes, right? I'm afraid that the value of an 11-year old Yaris will not dramatically change from an engine swap. You are also aware that your vehicle needs to be re-registered after the engine swap?
    – MadMarky
    Commented Nov 28, 2018 at 15:33
  • @SteveMatthews as long as the V7 field is below 130 and the registration date after 2006, it is eligible. The problem is changing the field. In order to change the engine, I need ask the permission to the manufacters. And manufacturers near always give the answer which will require buying a new car in the hope you will purschase it at them (because it is illegal to use a car on public roads with a different horse power than the one specified on the certificate). But again as serial numbers will be different too, I need to do this even if I replace the engine by the same model. Commented Nov 28, 2018 at 16:19

1 Answer 1


Looking at the two options you suggested in turn:


You're going to go screaming past that 50€ figure for ancillary changes I'm afraid - the 1NRFE will definitely need a new ECU, not only does it have the updated "Dual-VVTi" vs the 2SZ-FE's "single" but it also has stop-start (which is partly where the emissions improvements come from) so not only are you going to need a new ecu but a new battery, starter motor and likely a fair chunk of the loom will be different too. I'm also reasonably sure that the French-spec will have EGR as well which I don't believe the S2Z-FE had so there's going to be some exhaust plumbing changes going on there too.


There's likely to be some adaption involved in fitting this one - it's a 3-cylinder engine rather than the 4-pot 1.3 of the 2SZ-FE, which will likely mean changes to engine mounts, gearbox you should be okay (depending upon which transmission you have already) and again you're going to need a new ECU and there'll be some loom changes as well.

  • I have currently an electronic stick stick shift gearbox, but it current works well with my de-facto 3‒cylinder engine (1 cylinder is broken beyond repair which is why the engine needs to be replaced). Will I need to change the starter motor and the battery for the1KRFEmodel ? Concerning the1NRFEI’m sure the stop and start feature is always optional whatever the engine. Or at least in France. Commented Nov 28, 2018 at 15:06
  • @user2284570 I wouldn't have thought you'd need to change starter/battery for the 1KR-FE, you will need an appropriate ECU and engine loom though and ideally I'd say you're better off sourcing one that came out of a Yaris with the same transmission to make that easier. I'm not convinced there aren't going to be a handful of other minor changes to make that will make the 50€ changes budget unrealistic. Commented Nov 28, 2018 at 15:23
  • @user2284570 additionally if the goal is to bolster the resale value (by becoming eligible for the subsidy) then won't most of that be offset by fact that most people would run screaming from something that's had an engine conversion? Commented Nov 28, 2018 at 15:32
  • Yes, but I can’t keep the current engine because it is broken. Peoples would be screaming even if I replace the engine by a same model. Commented Nov 28, 2018 at 17:04
  • @user2284570 it might be a cultural difference.. here in the UK a like-for-like replacement engine is often a good selling point but anything with a conversion is viewed by non-enthusiasts as a huge negative. Commented Nov 28, 2018 at 17:06

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