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Avensis 1.8 Petrol 1998 Open Loop After Warm-Up

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Hi there,

Due to car lacking power checked lean burn sensor (4 wire zirconium type) . As engine warmed up had sensor output regular cross- over function ok, When hot engine went into "open loop" mode, i.e. 0.45v steady engine running but lost the closed loop as is required. Car has done 95000 miles so replaced with a new sensor, same result as above, seems to cross-over ok till warm then defaults to open loop mode.

No engine fault light on untill I disconnect the sensor and run engine. On reconnecting sensor, fault light went out. Engine still in open loop mode.

I seem to have no fault codes stored, so I am guessing.

In the meantime I shall replace the old sensor so as not to carbon up the new one.

Any ideas.

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Hi Philip,

When you say the car is lacking power, does the car feel like it is missing? I don't think there is anything wrong with your leanburn sensor. You replaced it with a new one and got the same result!

I had an issue and it turned out to be the HT leads breaking down. I would also check that the inlet vacuum switch was working and connected.

You went searching for the fault in a deep and expensive way. Keep the sensors because you can sell either the old or new.

As I said, if the car lacks power and stutters, check the HT leads. I noticed that my car did not like supermarket fuel until I changed the HT leads.

I hope this helps Philip.

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I also mentioned in the other thread with Anthony, that the catalytic converter could be blocked.

Another known issue is the crank position sensor could be a problem, but your car is lacking power.

I would still look at the HT leads first, if they have not been changed recently.

Anthony's problem is different though he is carrying out similar checks.

I hope you both find a solution and fixit.

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