Yaris 1.3 Sr

[Balal]

Help

I have a w reg yaris sr and it has overheating problem do u reckon it is to do with the fan as it is not kickong in i have checked the fues there ok so and when car is in neutral and u try giving it a bit of gas the revs just drop and it seems just about to die out my dad reckon it is a oxygen sensor PLEASE HELP

[Paul E]

May be two separate problems. If the car is overheating check the obvious - coolant levels, thermostat, fan. When the temp goes up the fan should definitely cut in, so if it is not doing this that is your first problem. Even if there is enough coolant visible in the overflow tank you may have an airlock. Or a radiator or hose leak - can you see any coolant dripping, or dried coolant stains? Make sure you top up with proper Toyota antifreeze, otherwise you may get corrosion which can also lead to overheating.

Difficult to say any more without more details.

MAF or O2 sensor faults should cause engine management light to come on - do you have this light lit? If so you can use an OBDII reader to diagnose the fault.

Paul

[grin factor]

Is the problem with revs dropping only when the engine is hot?

[Balal]

Is the problem with revs dropping only when the engine is hot?

Both hot and cold

[Balal]

May be two separate problems. If the car is overheating check the obvious - coolant levels, thermostat, fan. When the temp goes up the fan should definitely cut in, so if it is not doing this that is your first problem. Even if there is enough coolant visible in the overflow tank you may have an airlock. Or a radiator or hose leak - can you see any coolant dripping, or dried coolant stains? Make sure you top up with proper Toyota antifreeze, otherwise you may get corrosion which can also lead to overheating.

Difficult to say any more without more details.

MAF or O2 sensor faults should cause engine management light to come on - do you have this light lit? If so you can use an OBDII reader to diagnose the fault.

Paul

What details would you need ?

Where is the O2 sensor

[Paul E]

OK you say the fan is not kicking in, so that sounds like you need to sort this first. if the fuse is OK then that points to the fan either being blocked or maybe a connector has come loose, wiring is abraded or the fan motor has failed. If you have access to a test meter or a friend who has one than you can check these. Rather than run the engine until it overheats, test as much as you can by checking continuity of wiring, feed the fan motor with 12v supply and see if it runs.

I would definitely sort your overheating problem out quickly, you don't want the engine to run too hot for very long or you risk damaging it, eg warping the cylinder head.

O2 sensor - I'm not sure on a 2000 Yaris SR, but typically there are 2, they look a bit like spark plugs screwed into the exhaust pipe, there will be one before and one after the catalytic converter. If the o2 sensors have failed they will trigger an engine warning light, so if you don't have this light illuminated it is very unlikely to be your o2 sensors which are causing your problem.

Good luck

Paul