bl817

hey all. p0340, p0339, p0344, p0141, p0420. trying to help a buddy with his 2005 civic special edition 1.7. car was stumbling and finally died in traffic. got it home and codes read in that order. so far ive had him pull and check the battery. still waiting on results. from what ive read, has the cat gone out and destroyed the downstream O2? cam and crank sensors going bad at the same time sounds unlikely to me. haven't had a chance to test any circuits, just going by all the reading ive done so far. the "tech" at the parts store where he pulled the codes said could be possible loose timing belt. car has 145k miles and original TB AFAIK. any insight/advice would be greatly appreciated before just throwing parts at it. thanks again.

ezone

I bet the CEL has been on (and ignored) for a long time, before something new went bad and it ran like crap. NOW you get to see all the codes that have happened since the battery was last replaced... 5 years ago.
Ya?

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P0340 CMP no signal
P0344 CMP intermittent

P0339 CKP intermittent

These seem to have a couple common points, the two sensors share splice pack junctions with the injector power for their 12v+, and another group of splices for their grounds.... and the power for both sensors and the fuel injectors (and more) comes from the PGMFI main relay #1.

P0141 rear O2 heater circuit
P0420 cat efficiency

Sensor heater codes are common failures, likely just a bad rear sensor. Ohm check the sensor heater, is it open circuit?
The cat code had to be present before the sensor fault code happened.

If you unscrew the rear O2 sensor and find the tip that sicks inside the exhaust has been broken off, then you can suspect the cat came apart.


I'd erase the codes, then run it/drive it (with scanner connected) and see what code returns first and chase it that way. If the cam and crank sensor codes reset together at the same time, there's a good chance it's caused by something common to both items. If they don't set at the same time, it's gonna be a toss up.

I think the O2 sensor code will return first, very soon, like about 5 seconds after you start the engine.

bl817

thanks for the reply. I'm waiting to hear on the battery. will have him start car upon battery install/replacement and go from there. I'm used to working on my Mustang and Camry, this Civic is a different animal.

Carbuff2

The first three codes are about the Camshaft Position Sensor. I'd be prepared to replace that...intermittent faults will be a BIG inconvenience...the ECU will shut down the engine and leave you stranded!

bl817

p0340 and p0344 are cam position sensor related and p0339 is crankshaft position sensor related. ill be getting the car tonight or in the morning. going to start with the battery, then on to the main relay as ezone stated. will get it on ramps and use a rubber mallet to tap on the cat to see if it rattles then remove the rear O2 and check that. then look into replacing the cam sensor (how easy/difficult is that) haven't had time to research just yet. I advised that the timing belt/water pump should be replaced asap and a new crank sensor while the covers are off. thanks for the input/advise thus far. please keep it up!

Carbuff2

Both those sensors are easy to replace. Even without touching the timing belt. But if the TB is old, for sure... do that and the WP too.

bl817

will do. how involved is the TB/WP to replace. still new to the Honda and doing research. ive tackled a 2.7 santafe TB/WP in a weekend as well as head gaskets in a torrent so not opposed to digging in and tearing stuff down. once I get the car and check battery and other items, will post on results. I cant thank yall enough for the help, wanting to get them back on the road.

Carbuff2

Haven't done the one on the Civic yet (previous owner had it done 'on schedule').

bl817

as far as the cat goes, how vital is it to use the genuine part? they are super expensive and ive used walker with no problems. on the same note, what about the sensors as well. if things look bad and need most parts, will get an order together from rockauto.com and get middle of the road parts. BDW is out of the question as every sensor ive gotten from them was defective.

ezone

Be aware, the cat can be bad without rattling. The code only means it's efficiency has dropped below 'spec'.


Timing belt on this engine should be a walk in the park, other than the crank pulley bolt is pretty tight.
CKP/CMP sensors are all within the timing cover too. Watch out for the crank sensor connector, check for evidence of liquid entry/terminal corrosion if you unplug it. If not replacing that sensor, do not unplug it at all (the simple act of disconnecting sometimes causes problems)

You get what you pay for.
OE first choice, but that's not cheap.
California C.A.R.B. approved is better than the cheapy 49 state and should have a better warranty.
Many cheap cats won't keep the computer happy long enough to get past the one year warranty, and they usually don't cover labor when it fails.

Cat, sensors, whatever.....I use dealer parts-- because I work for a dealer. My 'comebacks' (failures) are just about zero.

I DGAF about the parts stores' lifetime warranty.
(Most people tend to believe that lifetime warranty means one thing. To me it means something totally different.)

If you want OE quality, use OEM parts. Oxygen sensors will be DENSO or NTK. Scrape the crud off of yours and see who made it. Look up that manufacturers website and find the part number for your application. Google that part number.



IF you want to replace the timing belt tensioner pulley and spring, USE ONLY HONDA PARTS. (many inferior parts are on the market and too many just don't last, ....some don't even make it to the next oil change....... catastrophic failures)
The engine will bend valves if it jumps time too far, so anything in the timing area needs to be top quality if you expect it to live a long happy life.


JMHO, YMMV

bl817

having the battery tested shortly. there is definitely something wrong emissions wise, the exhaust smells rich. will suggest replacing the cat and rear O2 to start with. will probably start with the O2 and go from there. this car has 145k on all stock parts (except plugs and oil.)

ezone

Fix all other problems first.
Cat should be THE VERY LAST replacement.
If the engine does not run perfect, the best cat in the world can be ruined in just minutes.

Carbuff2

Does the Civic 1.7 require the tool to remove the crank bolt? (Sometimes these things are available on loan, at AutoZone or other parts stores.) Be Prepared (like a Boy Scout).

X2 on using only the Denso or NTK (NGK) sensors. Other brands might be a lot cheaper but are not 'wide-band' as most Hondas require.

bl817

had to get a new battery. the downstream O2 had the tip peeled back. I'm pretty sure the cat is toast. should I be able to see the element thru the O2 sensor bung? it looks like a few shards have broke off. didn't have denzo at the parts store, got a bosch. the cat for this car is integrated in the exhaust manifold so should be easy swap out. thanks for the info fellas

Carbuff2

Bosch sensors are troublesome in Hondas. Good Luck!

bl817

well hell, ill keep my fingers crossed that I'm not replacing it in a few months. I highly suggested for them to replace the cat altho the Honda part is a grand. thanks again fellas for all the info and advice. I also told them that once they can afford it to get the TB/WP done.

ezone

If the tip was missing, the cat probably broke apart.

Any loose cat pieces bouncing around in the exhaust may damage another sensor. Either replace the cat, or make sure the cat is gutted and completely empty as a temporary solution, and the rest of the exhaust pipes and mufflers are verified empty of broken cat pieces. (This will continue to cause P0420 codes though)

Broken cat pieces bouncing around in the exhaust can cause it to run bad (limited power) if they clog the pipe somewhere and the engine can't breathe.

I'd make sure the cam/crank sensor issues are fixed before replacing the cat and O2 sensor, because poor running can ruin another cat.

Carbuff2

Don't forget to use some copper anti seize (so that you can remove the sensors again in a few months)!

PS, I understand the costs involved. As I said, good luck.

bl817

the tip wasn't missing, it looked like it had been melted and exposed the inside element. I'm thinking that the cat element being down so far melted it. the cam and crank sensor codes have not come up after replacing the battery. funds are tight right now and keeping them on the road is the first issue. I used nickel anti-seize on the threads, just a dab. the car runs and drives fine, idles fine, no real issues since it died in the middle of the road. like I said (I think) I'm hoping the new battery fixed those sensor issues. I cant thank yall enough for pointing me in the right direction and getting this car up and running, well for now.

bl817

ok so after driving for a few miles, upon parking, just prior to turning off the engine, I hear a metal clank and then the damn CEL light comes back on. I'm thinking the bad cat melted the tip of the new o2 sensor and sent it down the exhaust pipe. this is a 1 cat car so no damage downstream I'm hoping. advised owners to get new cat and NTK downstream O2 sensor from rockauto. I also advised that an oem cat would be best but for 1k it was up to them on what one to get, let them know that a carb unit would be better than non carb. thanks for all the help.

ezone

Got pics of this melted sensor? The sensors are designed to live inside the exhaust system so I'd think they should withstand some seriously high temperatures....
Broken, I can understand.
What codes does it have this time?

bl817

Didn't read codes. Had him park it.

ezone

Freekin wow. Thanks.
That almost looks like the metal tip was torn in half.

Maybe it's got Gremlins....lol

bl817

yeah, my thought is that the cat element broke apart and settled down closer to the downstream O2 sensor. still doing its job and getting red hot heated up the case and melted it.

RustyShackle

Jesus - that O2 sensor has seen brighter days.

Wankenstein

He's the kinda guy Marisa Tomei goes for.

bl817

back again smart ppl. so replaced the cat (OEM was a maraca) with a Cali approved unit, and NTK downstream sensor. car started and idled great. thought we got it goin. next day, car comes up to temp and starts acting up and throws CEL. had owner undo the battery overnight and run it next day to get codes. P0340 only. will be checking the voltages in the connector soon.

ezone

P0340 is cam position sensor..It has not been replaced yet?
Sometimes they do fail when they get warmed up.

I'd lean toward getting a new OE sensor.

Carbuff2

Yeah, OEM is what I would go with.

Seems as if the favorite on Rock Auto is a Dorman sensor, around $30 USD.

bl817

sorry no, i forgot about the p0340 code by the time we got the parts orders and installed in the car. should i voltage check the connector for the cam sensor or since its thrown codes multiple times, just go ahead and replace? thanks again for help.