Toyota Yaris (1999 - 2005) - 99 1.0 P0172 - Mixture too rich

Honest John Back Room » Technical matters
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Tue 21 Jul 2009 00:34
99 1.0 P0172 - Mixture too rich - ukspace
I've had this vehicle for a number of years now, regularly serviced etc but when I first got it, within the first 100 miles the engine light came on.

I bought an OBDII reader and found it to be P0172 - mixture too rich. I cleared the fault thinking i may just be a one off but over the years it has returned a little more regular. Up until about 4 months ago it would return after about 4 or 5 months but now appears within 2/3 weeks.

Although the fault doesn't affect the cars running I will be looking at selling soon and do not want to sell with this fault still present. I remoed and cleaned the MAF sensor today as some sites advise this and also cleaned the Lambda sensor as I am told this is responsible for calculating the Air/Fuel mix at emission stage.

A few things did make me puzzle. with the engine running, the unplugging of the MAF sensor caused the engine to stop with fault P0110. But when the Lambda sensor was unplugged with the engine running - no fault occurred. Does this sensor only get noticed at certain running times?

Any other advice for the P0172 fault code and it's cause/remedy
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Tue 21 Jul 2009 21:32
99 1.0 P0172 - Mixture too rich - Javalin
blocked/restricted air filter?
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