2015 Impala the Check Engine Light was on , code was P0496 and P0422, dealer replaced the puge solenoid said they found it was not sealed/leaking. Next day CIL back on with new code P0430. Said they found exhaust front flex pipe cracked and leaking. Next day CIL is back same code P0430. So I’m already $1000 into repairs and getting frustrated. I bought a OBD scanner on Amazon just to try and get more info and save a trip to the dealer or Autozone when the light comes on. How do I interpret the Freeze Frame data? It’s a Motopower scanner their manual and website kinda useless.
It tells you basic things like vehicle speed and throttle position at the instant that a particular P code fault was detected. It helps you know how to reproduce the problem.
Yeah thanks I know what Freeze Frame Data is and what it’s used for. My question is what some of the abbreviations stand for. Some are obvious like RPM, CATEMP, and some I located on other sites but some I have no idea what they stand for and what they should read under normal conditions without CIL on
Thanks tester I found a few there
Suggest to post the freeze frame data here, folks will probably have some ideas what the parameters and abbreviations mean.
It’s possible the defective exhaust pipe problem caused the 0430, and now the exhaust system is fixed the code won’t come back. The most recent and persistant 0430 might be a phantom in other words. Suggest to give it time to go away. Has your shop used the standard methods to check the entire exhaust system for leaks? It has to be air tight from the exhaust manifold all the way to the tailpipe, otherwise air gets sucked in during exhaust-vacuum portions of the engine cycle. I’ve had a helper semi-obstruct the tailpipe while I crawl under the car and feel for exhaust leaks, sometimes with a paint brush and can of soapy water.
It’s possible of course your cat converter is shot. In that case both p0420 and p0422 may refuse to exit the premises.
The p0496 means the purge valve is allowing evap gasses to pass into the engine at a situation when it shouldn’t. Usually the purge operation only occurs when accelerating or diving at highway speed. Not sure how computer knows it is allowing the evap gases to pass through. I wonder if that means the computer is able to read the solenoid’s electrical activation signal, and noticing it is being activated when it shouldn’t be. Otherwise a purge valve allowing the evap gasses to pass seems pretty innocuous from an engine management view, but I guess that could cause richer than normal operation which might eventually damage the cat.
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I hate to be the one but. If you don’t even know the acronyms, the numbers will be useless. Freeze frame data is one of those things that you either know how to interpret or you don’t. You need to know not only what they are at the time but what they should be given the other parameters at the time. Quick over simplified example, if the engine load says 37% and rpm is 2400, do you know approximately what the range should be for the MAF/MAP, O2 sensors, ignition advance, or others? It takes experience and knowledge. As suggested by @George_San_Jose1 you can post the data here and get some answers.
Yeah I’m not a mechanic and don’t know enough that’s why I’m here just looking for advice, my scanner has no print function I took some pics and stitched together
The P0496 and P0442 codes went away after the purge solenoid was replaced then it started throwing P0430 which wasn’t there before. Replaced a cracked pipe and P0430 still there so maybe leaking elsewhere I’m hoping it’s not a bad catalytic converter
TP_B % : These four relate to the throttle position drive by wire system
APP_D %
APP_E %
TAC_PCT %
LNGFT2 (%): Long term fuel trim bank 2; i.e. % change in the amount of fuel injected, comparing actual (which meet O2 sensor requirements) compared to what would be required only based on intake airflow.
FRP (psi): Fuel rail pressure
MAP (in Hg) Air pressure measured inside intake manifold. Atmospheric is about 30 inch, so 13.2 means there’s an appx 30-13 17 mmHg vacuum, normal for engine idle. There’s a BARA parameter upper right, which is the current atmospheric pressure, 29.2 in your case, like I say close to 30 mmHg.
RPM: You already know what that means.
LOAD_ABS: Explained along with most of the other parameter here
The important parameters for your problem are the
LTFT & STFT. If you have two exhaust banks, there’s one of those for each bank. I don’t see the LT for Bank 2 in your list, but some are pretty hard to read in the photo. The 3 fuel trims shown look ok though, no obvious problems.
Your scan tool provides other fuel trim data, parameters I’m not familiar with.
The other important parameters for your problem are the pre & post cat O2 sensor readings. To be diagnostic you need them graphed out as real time signals to make any sense of the data. Is your scan tool able to do that? See the note about fig 3 page 57 in the link in section: Oxygen Sensor Output Voltage B1S1, B2S1, B1S2, etc.
Suggest if you want to learn more about how to interpret the scan tool data, to type the parameters and values in a post, so they are easy to read and reply to.
I don’t see any obvious problem that points to a p0430, but that’s usually diagnosed with the o2 sensor graphing method. If you can’t get that graph, you’re going to have to just poke around to figure out if there are any exhaust leaks. If not, cat probably needs to be replaced. Sort of unusal for a 2015, but still possible. Like I say the evap problem could have damaged the cat. I notice your ltftbank 2 is 7.8 %, which is on thehigh side, but not entirely out of range. Suggest to use that as a clue to focus you inspection on the exhaust system parts on bank 2.
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Great info George that’s what I was looking for ty! Yeah I’m hoping it’s a leak it’s in the shop now my goal was just to be informed so I know what they’re talking about and don’t charge me for parts I don’t need
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Keep us informed what you find out … best of luck.
It was the catalytic converter after all. Finally talked to the tech instead of the ‘advisor’ asked him about the age 75k miles if it’s was unusual he said he’s replaced a few with and it’s always the one that’s mounted near engine not the other one. And they are covering it I lucked out on that maybe all my complaints paid off lol
Good for you, great job, cat’s purring, wallet’s fat, happy motoring. Bank 2 cat?
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Yes George was Bank 2
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