Toyota Yaris 1.0 VVTi oxygen sensor

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Thu 5 Oct 2006 14:48
Toyota Yaris 1.0 VVTi oxygen sensor - Insect
The engine management light on our Yaris is permanently on. We've had a diagnostic check done by a local garage, who say that the fault code indicates a lean mixture, but they can't find anything wrong.
Looking at other info, it seems to be reasonably common that the oxygen sensor on the Yaris plays up. Would this cause the 'lean burn' fault code to be displayed, where is the sensor and can I check it - or is this a job for a specialist?
Thanks for any help that you can provide!
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Thu 5 Oct 2006 15:51
Toyota Yaris 1.0 VVTi oxygen sensor - Aprilia
Yes, could be the problem. Could also be an air leak into the exhaust up-stream of the EGO sensor.

The sensor can be tested fairly easily by looking at its signal on a 'scope (should switch 0.2-0.8V approx., at around 0.5-2.0Hz at idle - up to 2000rpm). ECP do a cheap clip-on O2 sensor tester for about £17. A suitable scan tool would show live readings.
If you're sure its the problem then you can buy a new one and fit it - it helps to have a slotted 'ECO sensor' socket to undo it which has a slot for the wires to pass though. Its located in the downpipe.
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Thu 5 Oct 2006 18:05
Toyota Yaris 1.0 VVTi oxygen sensor - Insect
Aprilia
Thanks for your response. I don't have a 'scope, or any electronic diagnosis gear, so this looks like a job for a specialist. Would you use a Toyota dealer or is it better to go to an auto-electrician?
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Thu 5 Oct 2006 22:21
Toyota Yaris 1.0 VVTi oxygen sensor - Aprilia
'Auto-electrician' is a bit of a vague term - there is an auto-electrician near me who has an old Avometer and a few screwdrivers - I wouldn't trust him to fit a new battery for me.
Try to find someone who specialises in engine management (many Bosch agents) or an Autodiagnos agent. Obviously Toyota can do the job, but at a correspondingly higher price.
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Thu 5 Oct 2006 22:26
Toyota Yaris 1.0 VVTi oxygen sensor - cheddar
A neighbour has had a similar problem with a 1.0 Yaris, the dealer seems to simply clear the fault code though not get to the bottom of the problem, frankly they are finding the dealer a pain. I will mention the oxygen sensor point.
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