Hi Everyone,
I own a 2016 Mazda CX-5 (GT) with 170,000 miles on it. For the past two months, I've been experiencing RPM fluctuations between 750 and 2500 while idling. The issue doesn't seem to occur while driving.
I ran the codes for the check engine light, and it's showing P0171 and P0300. I've been getting these codes for two months now.
Prior to this issue, I replaced the coils and spark plugs, as well as the air filter. I tried replacing the coils again, which initially seemed to resolve the problem, but it returned after a while. Note that these coils are not OEM parts. The first set was from AA Ignition, and the current set is from NGK. My spark plugs are also NGK, and I've ordered a new set of genuine Mazda PE5R-18-110 Iridium spark plugs, but they haven't arrived yet.
Additionally, I've noticed that when I fill the gas tank, the car has trouble starting. It appears to be a battery issue, but after pressing the pedal a few times, it eventually starts. Then, I need to maintain a high RPM to stabilize the engine before it runs normally.
Has anyone else encountered similar issues? Any insights would be greatly appreciated. I'm quite frustrated, especially since this is my family's only car.
Thank you all in advance for your help!

 

I can only "guess" with the little bit of info you provided.
Have you replaced your fuel filter and checked that your fuel pump is operating correctly?
With those miles you could be looking at injector issues as well.
Really good batteries in a CX-5 only last 3-5 years and the OEM even less time.
You would be better off taking to a trained technician and get the correct diagnosis instead of throwing parts and money at it.

 

Hi Lobstha

Here are the answers.

* Have you replaced your fuel filter and checked that your fuel pump is operating correctly?
No.
* Really good batteries in a CX-5 only last 3-5 years and the OEM even less time.
The battery is one year old.
* You would be better off taking to a trained technician and get the correct diagnosis instead of throwing parts and money at it.
I have already taken to 2 places but they were not able to provide the issue.
One of them replaced MAF sensor and nothing, So they put the old one back.

 

LOL ok then let me try to answer in that fashion?
Stop repacing parts that are not confirmed to be failed or failing. Doing this GUESSING and replacing random parts not only cost you money but is likely to create new issues on top of the yet determined unresolved ones.
The age of a battery is in no way indicative of its present state.... GET IT LOAD TESTED
Taking any random service shop that does not have at least one employee that is a certified Automotive Mechanic (in the last 5-10 year no older) and more importantly Diagnostic Automotive Technician with your year Mazda is a waste of everyone time (yours and any forums included) time your money.
Because your reported and unconfirmed as active DTC(dignostic trouble codes)

The only factual advise I can say is because you have a logged in your ECU at least the common area a PO300 indicates to me you have things going on that are creating anomalous conditions reporting to the ECU that fiorst needs to be confirmed by resetting all DTCs and the I/M monitors then a complete engine cycle needs to be done and or until the engine check light returns or if live scanning a indicator of something wrong shows.

In other words, go back and re-read the first part of my response to here again!

 

This tells me you have not taken your vehicle to a qualified technician.
A qualified trained Mazda tech will find the issue or issues.

 

I appreciate you taking the time to share your expertise and provide advice on addressing my automotive issues. Your insights are truly valuable.
However, I would like to respectfully point out that the tone and choice of words in your response may come across as harsh to some individuals. It's possible that you might not have intended to be rude, but some phrases and the use of capitalization may be perceived as impolite or insensitive.
We all value constructive and helpful feedback, and maintaining a considerate approach while communicating with others can make our interactions more pleasant and productive. I understand that you aimed to stress the importance of proper diagnostic procedures, and I assure you that your advice has been well-received.
I hope you don't take offense to this message; instead, please see it as a friendly suggestion to foster a more welcoming and positive environment for everyone seeking help and sharing their expertise. Thank you again for your valuable input.

 

I get told this often This is how I write simple as that. You can not see my demeanor and more importantly my body language. I am straight to the point and don't SUGAR COAT my responses. I am not helping to win a popularity contest, and I really don't have time givi9n that I not only am at work, but I participate on several different vehcle related forums to help members the best I can.
ITRW (in the real world) I have often over decades been told I have great custom service skills. But see how that works.... ^Re-read above^
Thank you for your input it always noted. I can see that perhaps you exceled in high school or perhaps college in the use of Grammar and writing skills. I went the other way
Trust me I write so bad that spell check freezes up and my check grammar and spelling 30% is often highlighted in RED. LOLSomething to consider you are a new member, Join Date Jan 6, 2025 Total Posts 3And me....Join Date Oct 20, 2018 Total Posts 6,951
Here is a great thread you can learn about a few members as well maybe you can post something as well.
What do you do or have done for a living - Mazda Forum - Mazda Enthusiast Forums

Again, thank for the input, but I am not really changing my responding methods.