My Yaris is due for an MOT this month. The last MOT report says that CO is right on the limit, everything else is normal HC, Lambda etc., as shown below.

The CO has been creeping up every year, and the code P0172 has recently came up which means "System Too Rich".

The car is 19 years old and when it's first started I can smell petrol outside and sometimes when I get out after driving it I can smell it too. I've tried Cataclean and i've also cleaned the MAF.

I'm thinking it's the CAT? Any thoughts?


Emissions Report

  • Welcome to Motor Vehicle Maintenance & Repair! Have you changed the O2 sensors or still running the original ones? – Pᴀᴜʟsᴛᴇʀ2 Mar 4 '18 at 14:37
  • @Paulster2 Thanks! The pre-cat sensor is 2 years old and the post-cat sensor is 10 years old. – Ross Mar 4 '18 at 14:41
  • The post-cat wouldn't have much to do with it, but the pre-cat would. Seeing as how it's only 2 years old, I wouldn't think it would be an issue. Have you checked for vacuum leaks? Are there any exhaust leaks? Have you cleaned your MAF? – Pᴀᴜʟsᴛᴇʀ2 Mar 4 '18 at 14:49
  • @Pᴀᴜʟsᴛᴇʀ2 - Yes, there doesn't seem to be any vacuum or exhaust leaks. I've also cleaned the MAF. – Ross Mar 4 '18 at 14:50
  • Also a fuel pressure leak down test... Possibly a leaking injector? – SteveRacer Mar 4 '18 at 15:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.