RAV4 2013 Emission test fail

Please help a COMMUNITY NEWBIE and a car user who never worked on a car (ME) in the Middle East (Saudi Arabia)

Struggling to get my 2013 RAV4 with 171000 km cross the line on the emission’s test. Things my mechanic has done uptill now:

1- changed the spark plugs because they were black on tips (after 6 months use)
2- changed the airflow sensor and the water pressure sensor even though we had no check engine light or any issue on the scanner.
3- changed gasket on the head cleaning top of the pistons and the part behind the block where the mixture is made (I think)
4- changed the fuel form 91 RON to 95 RON when 91 RON is devised by the fuel provider (ARAMCO)

The target CO value is < 3.5 and after making the above changes my car’s figures have gone from 7.6 to 9.9 :sweat_smile:

Have your mechanic check the fuel trim data.
That might give a clue to what’s going on.

Carbon monoxide is a rich indicator

So you may want to think about what is making the exhaust rich

So is sooty spark plugs. Were they wet with oil, too?

You might consider new coils as well.

Compression test?.. And was the correct OEM spark plugs installed??

Have the mechanic check if the O2 sensor is functioning correctly.

Faulty oxygen sensor - These sensors monitor the mixture of air and fuel in the engine and make adjustments as needed. With faulty oxygen sensors, drivers will experience issues like reduced fuel economy and increased emissions. In the case of the RAV4’s faulty oxygen sensors, the main culprit is wear and tear. Although they can last up to 100k miles, they can sometimes break sooner. The recommended fix is replacing the sensor, but ensure you have the right sensor type for your RAV4 model.


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Good ideas above. I’m guessing a fuel trim test has already been done, suggest to ask your shop for that data and post it here. It would be hard to believe a shop would remove the cylinder head and clean the tops of the pistons without first doing a fuel trim test.

If the fuel trim tests says the fuel mixture is too rich, likely causes are

  • Engine coolant temp sensor is faulty (perhaps this is actually the “water pressure sensor” referenced by OP)
  • Fuel rail pressure is too high
  • Fuel injector(s) leaking
  • MAF sensor is faulty or dirty
  • Engine air filter clogged
  • Evap system problem, especially purge valve
  • O2 sensor faulty
  • Exhaust system not flowing freely
  • Engine cylinder compression is too low (internal engine problem)

Higher octane fuel is unlikely to help. Suggest to give up on that idea. A fuel injector cleaning procedure or treatment might help though. It doesn’t pertain to the exactly same problem, but it might still be helpful to read through the following thread.

Thank you so much for all the suggestions. I will work with the mechanic to check these things out and report back soon.

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Suggest to also post the rest of the measured emissions data, NOX, and HC. Might provide another clue to what’s going on.

Also remember that this forum specializes mostly in USA-sold cars , which yours presumably isn’t. Your engine may be configured differently than USA Rav4’s. Pop the hood. There is likely an emissions sticker on the underside of the hood. Suggest to take a photo of that sticker and post it here.


I got these data screen pictures (24MB data so had to upload on a onedrive folder and insert the link into word ‘pictures’) of the scanner and in terms of my mechanic’s (who has no formal education) ability to understand all these numbers and their description is non-existent.

So if you or other community members could make sense of them or advise me of further tests, use a different scanner that will be great.

Thank you once again for all the help.


On the very first screen shot, a few things caught my eye . . .

F/B correction ratio -16.407%
F/B learned ratio 19.531%

From the data, it appears you have a 4-cylinder engine and I’m speculating these particular PIDs might be for fuel trim . . .?

A few pages later, it says the catalytic converter temperature is around 322 degrees fahrenheit, which correlates to 612 degrees fahrenheit, which seems only marginally warmed up, as far as a catalytic converter goes

Has the car been properly pre-conditioned before the smog inspector begins his testing?

Have you driven the car several miles to get everything properly warmed up before arriving at the smog inspection station?

You’re not just warming the car up stone cold in the morning and driving to the smog inspection station at the end of the block, are you?

The Motor Vehicle Periodic Inspection (MVPI as it’s called here) centre is 33 km from where I live and I have been driving straight to the centre using roads with speed of around 100 km/h from a cold start at home.

Do I need to drive more miles/kms to get the catalytic convertor warmed up?

Yes. You should drive for at least a half hour on a highway to properly warm up the car before having it tested. You probably need to double or triple your drive to achieve that. That’s what my local DMV recommends.

OP, since you can view the data in Word, suggest to just make a screen shot, and upload a jpeg or gif photo so everyone here is able to view it.

If you don’t know how, ask. Quick summary: Hit the “print screen” key on the keyboard, then pasting what it captures into a photo application , like M/S Paint.

Or just post what the measured HC and NOx levels were.