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Discussion Starter #1
Never had any problems with the car. Couple weeks ago started a loud tap or lite knock. Was Going to adjust the values. Then check engine light comes on. Scan tool said codes p0240 catalyst system efficiency below threshold B1 and code p1659 ETCS control relay off malfunction. Was told p0240 was catalytic converter which is 4 hundred .need help to know what the codes are and how to check to see what is actually happening. Wondering could the tap have something to do with the code. Would appreciate help in what steps to take before buying expensive parts for no reason. Highly appropriate any insight.
 

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I don't see a P0240 in my manual, but there is P0420. And you're right, besides fuel quality the troubleshooting ends in "replace the three-way catalyst". It also mentions that if some other codes are present, then fix them first since P0420 might be stored because of them. However, P1659 isn't one of them.

P1659 has a pretty lengthy tree, but it mostly tells you to check Fuse 21 and make sure it is good (it is in the underhood fuse box). If it is good, it then mentions checking the ETCS relay (in the same box). Beyond that, it has quite a few checks for broken/shorted wires, and then it points to the ECU.

So maybe check that fuse and relay first.

Good luck.
 

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Update mechanic said I have a cracked block. All he did was put it on the lift and listen to the engine. My question if I had a cracked block won't I loose power and compression?
 

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I'm not sure how he/she could determine it was a cracked block by just listening. Perhaps he needs to tell you where it is cracked.

Although it was supposed to be fixed by 2008, the early Civics had a block porosity issue that required block replacement - you can search and find that topic lots of places on this forum. But as I understand it, it was never an audible failure - just had coolant leaking out through the block wall.

Now, if the block cracked where one of the engine mounts is attached, that might cause a tap and he might be able to see/hear it from underneath the vehicle. But I'm not sure how that would drive an emissions code unless that P0420 was just a coincidence.

Regular knocks or taps within the engine are usually a rod bearing or piston pin bushing failure. When someone says they have a rod knock, that often means a rod bearing is damaged.

I'd want to understand more around where the block is cracked.
 

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Thanks glen t .he did put it on a lift and said that engine had a history of the block cracking and said cracked between the cylinders. Still I thought if you got a cracked block you gone loose fluid and or at least you would lose compression and power. If I do a compression test will that tell me if my block cracked
 

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If it is cracked between cylinders, then I would think you would have coolant getting into your oil. If it is cracked externally, then you would have coolant leaking out on the floor.

A compression test won't hurt, but depending on where the crack is, it might not detect it.

I'd watch for an external coolant leak, or a mixing of fluids (i.e. oil in your cooling system or coolant in your oil. For the latter, you usually will find a nasty milky gray gunk on the underside of your oil fill cap.

Still am a little skeptical that he could just hear a block crack.

Perhaps you should search for block failures on this forum and you will then have more info to go on. I thought this engine had a history of porosity, not cracking and the general consensus was that Honda had that issue fixed before 2008.
 
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