2010 Mazda CX-7 SCR warning

Dear Car Talk
I own a 2010 Mazda CX7 Diesel. Ive just had my third diagnositic with Mazda @ $165/hr to now be advised that the installation of a R2AX-18-JHIA NOx sensor should rectify my intermittent SCR warning problem. The cost for the sensor alone is 4176.00. I’m asking for a quote to complete the task but as you can imagine, my faith in Mazda is lacking (seriously). My question(s), am I a very unluckly vegemite and this stuff just happens or am I being ripped off by Mazda cos I knows nuffink?
I am seriously stressed. Thanks for listening - Vi

The same answer each time? If so… why pay for 3 of them? Or all to address the SCR (don’t know what that is) problem and you got different answers each time? I am confused as to why you’d pay for this 3 times.

Why is that? Because it took 3 tries to find an intermittent problem or because the cost of repair is so high?

An honest business will not rip you off. If you think they are not honest, go elsewhere. This car is out of warranty, so take it to an independent mechanic rather than Mazda. An incompetent business might very well repair the wrong part and waste your money. You didn’t provide enough explanation to make that judgement. And finally, cars are complicated and can be difficult to repair ESPECIALLY if the problem comes and goes (intermittent). Take it for what it is worth. Good Luck.

Thanks for your response Mustangman.
Despite the revisits I only paid $165.00 as two Mazda fixes failed - after the third visit, Mazda Melbourne are of the firm belief that the NOx sensor will be “the fix”.
Thankfully I do have a mechanic whom I trust who has maintained the vehicle virtually from purchase. He can purchase the mazda sensor at trade price including GST for $3200 so my solution is a no brainer when Mazda Liverpool have quoted part and labour at $4780.
I maybe nothing but a number to Mazda but gullible I am not.


The Selective Catalyst Reduction filter is what reduces the NOx emissions.

If the SCR is functioning properly, then the problem has to be with the NOX sensor.


Appreciate the assurance. It’s stressful when you no nothing about this stuff!

Not much in the way of diesel engines in 2010 Mazda’s in the USA. Mercedes has a diesel 2010 GL350 that uses a nox sensor though. Sensor parts cost is $500-$600 each, depending if you want the front one or the rear one. So I don’t understand why it would cost nearly 10x as much for a Mazda sensor, unless you are referring to some other currency rather than US dollars.

Cost is in Aussie dollars and I can’t explain the cost either. A mazda is not what I would call a luxury vehicle.

is about $2200 US, still a good hunk of change, much more than the Mercedes part costs. Of couse the Mazda part may do more stuff or do it more accurately than the Mercedes part. It’s the price we pay for modern car’s high tech.