Avensis 2000 Oxygen Sensor - Advice Please

[Super Tyke]

I have an Avensis 1.8 - 2000 year (the early model with only one oxygen sensor). I am finding it very difficult to find a replacement sensor on eBay or from a breakers yard. I have seen adverts for Cat clean, or similar, which says it can clean sensors as well as the Cat. Would this cleaner reach the sensor on my model or should I keep looking for a replacement sensor?

Thanks for any advice - I am not mechanically minded.

[Devon Aygo]

If you have an early 3sfe 2.0 engine ( with cambelt not chain ) then the sensor in your exhaust is not actually an oxygen sensor it is called a lean mixture sensor and it works differently to an oxygen sensor, try asking for a lean mixture sensor.

[Konrad C]

Your car must have the 7A-FE engine from 1997-2000. Search using the engine name and 1999!

Most catalogues think that 2000 year is the vvti engine.

Euro car parts list the sensor - just type your reg.

As the engine is lean burn the sensor cost a lot more. I assume you have had sensor checked as faulty?

This can be done with a piece of wire. More of that later if you need to know.

[Super Tyke]

Thank you both for this information. I originally looked for lean mixture sensor but nothing came up so I changed my search to oxygen sensor. The car does have a cambelt.

I haven't checked the sensor and would appreciate advice on how to do it. The engine runs well but noisy under load, and there is a problem with the emission test so I was advised to look at the sensor.

[Konrad C]

So you were advised but not told specifically that the sensor could be at fault!

If the sensor is faulty, your EML (engine management light) will illuminate on the instrument panel. If the EML stays lit with the engine running then there is a fault logged and this is when you need to find what the fault is.

With pre-VVTI cars like the lean burn 7A-FE car you own, self diagnostics can be done without any need for a code reader (some code readers may not work with early Avensis).

The diagnostic socket is located behind the storage box near the driver right knee. Remove the storage box to reveal the fuse box, and the 16 pin diagnostic socket just above. Using a piece of wire or paper clip, connect pins 4 (on the upper row) and 13 (5 on the lower row). Then turn the ignition on, but don't start the car.

The EML, ABS, and SRS will blink. If the blinks are constant with no long gaps, then no fault codes are stored.

If the EML flashes a series of 2 flashes a gap then 1 flash, then repeats the sequence, the sensor is at fault.

This system was carried over from the Carinna, but does not work with the VVTI engines that followed. A free a easy check!

Now if the EML has not lit, then you should look at other things like the air filter, oil and oil filter change, spark plugs and HT leads. You should make sure the induction side and vacuum and breather pipes are good condition and connected.

Make sure the inlet vacuum switch is connected to the lever that operates the inlet valves has not disconnected, as mine did once.

Finally look at the exhaust system and catalytic converter.

Do the cheap fixes first and work your way to the more expensive ones. Do you do high engine speed driving? Town driving tends to cause build up of stuff that needs to be blown out on a fast run - Italian tune!

Lets hoe you find the solution.

[Super Tyke]

Konrad

Thank you for this very comprehensive guide. I have just discussed your list with a friend who knows about cars and will be assisting me going through it. We have a code reader but it hasn't come up with anything previously. I only do short journeys to and from work - 5 miles each way - with the odd journey up to 30 miles. We have had a couple of trips from Yorkshire to London since it started but it hasn't made any noticeable difference, although I don't drive very fast.

Regards

Roger

[Super Tyke]

I have tried the OBD 2 code reader but it didn't work on my Avensis. The EML has not been lit at any time but I followed the instructions with the following results:

The ABS and SRS lights blinked continuously with a steady rythm. The EMS light flashed in the series 1 - 2 - 2 - 4 and then repeated continuously. Anyone any ideas?

I have started going through the rest of your list Konrad and all seems fine so far. I have just bought some injector cleaner so I will try that before I start on the catalytic converter.

[Konrad C]

I have tried the OBD 2 code reader but it didn't work on my Avensis. The EML has not been lit at any time but I followed the instructions with the following results:

The ABS and SRS lights blinked continuously with a steady rythm. The EMS light flashed in the series 1 - 2 - 2 - 4 and then repeated continuously. Anyone any ideas?

I have started going through the rest of your list Konrad and all seems fine so far. I have just bought some injector cleaner so I will try that before I start on the catalytic converter.

I checked the code list from the numbers you stated, and from what you quoted the EML would have flashed 12 - rpm signal, then a slight gap follows by 24 - intake air temp sensor. Both codes relate to ECU which is not getting the correct info from the affected items. The ECU cannot give the correct mixture for a given engine speed, load and air temperature.

What this means that the related sensors have issues, or the there is a break in the wiring, or a short circuit.

The simplest and cheapest thing to do is check all connections and see if there are any wires, where the insulation has rubbed away exposing the wire itself.

There are known issues with the rpm sensor, but this usually stops the engine from running at worst. The air temperature sensor is located in the air filter box. I had to push mine back in, as it nearly fell out.

Hopefully it is just a bad connection.