What's up Honda forums. So I was playing around with my new scan tool and did a scan on a Honda I just acquired. I got it for the K24 engine.

I work on all my vehicles and wrench as much as I can when I have time. So if someone can tell me which of these can be catastrophic to the engine? I'm going to look each one up but trying to determine which I should attack first. I do have a CEL

Also just installed a touch screen , eBay Chinese deals. So lots of the communication errors I believe come from that.

Edit: I'm going to start with replacing injectors, plugs, and probe the battery and alternator voltages. Maybe even just swap alternator...2.4L 164,000 miles

The battery deal looks worrisome. Thanks in advanced






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It sounds like you want to replace a lot of parts, but I recommend only replacing a part when you are sure it is broken. I've seen a lot of brand new parts fail out of the box, and that can create a new problem and complicate diagnosing the original problem.

Your two PGM-FI codes are for the O2 sensor and not the injectors. I would not replace the injectors or coils as you have no codes for these components. I'd only replace the spark plugs if they are due. Take a look in your owner's manual as I think the interval is every 100K or 110K miles. You may want to call your local Honda dealership to get the service history on your car. Hopefully the original owner took the accord to Honda for service, so you can get their records.

The only maintenance items I'd do at first if they are due are an oil change with new oil filter. The air filter if very dirty and the cabin air filter.

The CEL is on because of the PGM-FI codes that are both P0139. That is the O2 sensor that is bolted into the catalytic converter. The connector for the O2 sensor is under your passenger seat. I'd first unplug that connector and check if your pins have corrosion or any liquid/debris in there. Clean with electrical contact cleaner and reasseble.

For the battery/alternator, you should do some electrical tests before replacing. It is possble the lost power codes were set if the car sat for a long time and the battery drained, or the battery was disconnected.

I recommend having your scanner clear all the codes, then drive the car around, then check which code(s) return. If you get the P0139 code returning after cleaning the connector, get the secondary O2 sensor from NGK wiht the electrical connector to avoid any issues. It may be pricier than the sensor you'd have to wire in, but it is worth the extra $.

Then you can tackle any other items individually as none of the rest are detrimental to your engine.

You can also stop by a parts store and have them test the battery/alternator/starter to determine if you have any issues with them.

 

Thank you for that information. I went ahead and bought the rear and front O2 sensors AND boy you are right! The front sensor is pricey at $156(NGK with wires). Supposedely the rear sensor was replaced and it has a new CAT. I will be able to tell when I get under it.This car will be my daily 4 cylinder for at least 1-2 yrs. I don't mind swapping parts where needed.

I will tackle the sensors and battery voltage probing and report back. As far as oil, oil change done and I went ahead and did the transmission fluid to. Allegedly the part and service have been done at Honda. The Carfax is clean with only 3 owners and some maintenance service reports.

Not a bad car at all.

Edit: Also in the Carfax it states the starter was replaced in 2023 but I'm guessing a refurbished possibly.

 

Along the same lines as before, the front O2 sensor isn't throwing any codes, so if it ain't broke, don't fix it. I'd only replace the secondary O2 sensor if the connectcor is making good contact. I'd only replace the front O2 sensor if you find the fuel trims way off using your scanner or the signal from the front O2 sensor is not oscillating. There are a lot of youtube videos on looking at O2 sensors and fuel trims. I'd consider sending back the front O2 sensor to save you time and money. My TSX essentially has the same engine as your Accord and the O2 sensor is the original at ~20 years old an 185K miles. I don't have issues with fuel trims, so I woudn't replace unless I noticed a problem.

As for the starter, look to see if there is a sticker on it if it is a rebuild and hopefully who rebuit it. I'm running on a Denso rebuilt starter going on 10 years without an issue. As long as yours works, leave it alone. Accessing the starter requires removing the upper part of the intake manifold as access is very restricted.

 

That's sucks. I installed the front sensor last night. Took about 10 min. That's what I love about these older cars. The sensor I took off didn't look that bad, but it did look worn and charred(not sure how to describe) so I'm just going to bite the loss on the sensor. Piece of mind I guess.

Edit: I did watch a video on getting to the starter not to bad. I've had to do worse. Luckily I do have a garage so I can stop and come back to it anytime. Also thinking of cleaning the injectors, one of the spark plugs was darker than the rest
I didn't remove the rear to see how it looked but that's a next step, remove and inspect connectors. Spray some dielectric cleaner and see if it improves. I'll YouTube the fuel trims to see what info I can gather.

I cleared the codes and I'll see what comes back after a few cycles. I did put a trickle charger on the battery, it's probably due for a replacement (2019) but I will check all voltage drops first.

I do have a question about the permanent vs temporary DTC? My TopScan reads more than a handheld one. But the topScan wouldn't erase the O2 codes, the hand held was able to erase them.
As weird as it may be, I do love trouble shooting... The time spent is worth it as opposed to taking it in to repair shop blindly with out any info.

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I'm just giving suggestions, because I've gotten into more trouble fixing something that wasn't broken expecially on a close to 20 year old car. If you replace working parts, keep the old ones, as you may need to reinstall later if the new one is bad out of the box.

For your question, a permanent DTC is set under certain criteria that can be different for each code. One criteria is how many times the PCM detected the problem. If the code has a criteria of 2 bad reading in a row when checked, the first bad reading will be stored as a temporary DTC, then become permanent when it happens multiple times.

I'm not sure why the topscan couldn't clear the codes, but I suspect the programming of the scanner is the issue. You likely need to search online to see if there is a workaround or something trivial to have the scanner erase the codes.

 

Here's an update: I replaced the front 02 sensor on Thursday. Erased the code with a handheld scanner. CEL pooped up the next day but I was anticipating it to disappear after a few drive cycles. Alas,it went away yesterday morning. Been off all day today. I reran the scan tool (TopScan) and it still reads a P0139 code same one. Permanent and temporary. I erased them today. The body electronic code all went away after placing the trickle charger on the battery. Today I read all voltage drops at 12.8V consistently at each ground point further and further away. The only code it throws is the window control which I could careless. But that's probably why my auto window doesn't work. Also, I have a question. Why does the engine sound like a weed whacker? Only upon acceleration from stop. I assume a bad vacuum hose or exhaust pin hole somewhere? I've tried to attach a video of sound. In the video it sounds like a whistle. In person my nephew asked "Woah you got a turbo installed" 🤣🤣 Car drives great though.

 

P0139 is dealing with the rear O2 sensor, so second O2 sensor. Did you only replace the front O2 sensor before the catalytic converter?

 

Ya I did. The one in the rear has been replaced already allegedly. But at least it's cheaper than the front.