P1121

what it is? just a code, or is something else broken?

 

ah, thank you. i don't see why anyone can't fix that, unless they need tech stream to bleed the system?

 

i think you can get the chinese tech stream cheap, from what i've read.

 

If the system is low on coolant it has been known to give this problem. Check the level of fluid in the radiator under the front plastic cover. "not the header tank" The radiator should be full to the top. If not top up with Toyota SLLC (supper long life coolant) nothing else. Then check the engine coolant pump for leakage.
Look inside the pump pulley for pink powdery deposits. If there the pump is leaking. Any garage should be capable of changing this as it is no different to any normal car, but is difficult to bleed any air out of the system.

John (Britprius)

 

This is because the fault is intermittent. The coolant control valve sticks and the coolant acts partly as a lubricant, and is probably why low coolant can cause "not in all instances" the problem. So yes the light could come back. The car can be safely driven with this fault providing it is not because of low coolant. As this could lead to overheating depending on how low the coolant is. So first priority is check the coolant level.

John (Britprius)

 

Yes code and CEL will come back if problem happens again. Coolant Control Valve isn’t critical item in a sense that if it fails even in worst possible position you will only lose most of cabin heat (electric heater is still working). So if code doesn’t come back I wouldn’t do anything since even if it fails you’re not going to be stranded.

 

The only problem with ignoring the fault is that if another fault appears there is only one warning light so you will not know there is an extra problem.

John (Britprius)

 

You read my post wrong. If CEL doesn’t come back on I would do anything. I wouldn’t ignore any warning lights.

Yes OP should also check coolant level like you said since it can also cause this. It should be checked from radiator and not from overflow tank.

 

Sorry yes I miss read your post. One question. Does the Prius in Finland have the PTC heaters? I know the US version does , but the European Prius does not nor do we have the coolant control valve or thermos tank.

John (Britprius)

 

PTC heaters yes. And also seat heaters. But no coolant thermos.

 

Thanks.

John (Britprius)

 

There are two filler caps close to each other. The one cap is on a container this is the reservoir. The other cap is mounted on top of the radiator closer to the front of the car, and this is the one we are interested in. You must remove the plastic cover to gain access.

John (Britprius)

 

First check the fluid level in the radiator. Remove big plastic peace by removing those plastic clips that have screw head in center. Then open radiator cap (engine has to be cold) Radiator Coolant Leaking a little bit, add black pepper powder? | PriusChat has picture of radiator cap removed. Fluid level should be what it is in that picture or maximum of (abought) one inch below that.

If level in radiator is correct then you need to get that coolant control valve fixed.

If fluid level isn’t correct then fill it back up with Toyota super long life coolant don’t use anything else. If half of quart isn’t enough to fill it back up then you probably need to bleed it (or get it bleed). If it hasn’t been low from when it was last serviced you should find out where its leaking.