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My 2004 Civic DX has 196,000 miles. Last year I put new front brakes on it and replaced all the suspension components. About 3 years ago it got a new clutch. I've had no issues with it starting and running. However, it does have a few things that need to be done, as well as some overdue maintenance, and I'm wondering how far I should go with it. So, my question is, when you have a big list of potential work to do on your car, how do you make the decision about how much to do?

Here's a list of what my car currently needs:
- Exhaust manifold/catalytic converter (current one is cracked and have the new one ready to install).
- Knock sensor (currently have code P0325 for knock sensor malfunction, new sensor arriving this week).
- Timing belt, water pump, tensioner (the current belt is 9 years old).
- Rear brakes

Overdue stuff that probably should be done:
- Spark plugs
- Fuel filter
- Valve adjustment
- Brake fluid flush
- Power steering fluid
- Coolant
- New crank and cam seals, and oil pump o-ring (might as well do that while I'm doing the timing belt).
- AC belt and power steering belt

Things I'm considering while I'm doing other things:
- New O2 sensors (why not, since I'm getting a new cat/manifold?).
- Clean fuel injectors
- New fuel pump assembly (since I have to go in there to replace the filter anyways, why not?).
- New coils (I believe the existing ones are original).

The "things I'm considering" (O2 sensors, fuel pump, coils) would probably cost around $550. All the other stuff is probably going to cost $1,000. How far would you go? Would you do everything? Would you just fix the broken parts like the knock sensor? Or, would you do something in between? And how would you decide?

Thanks to anyone who engages in this discussion and shares their thoughts! Oh, and for the record, there is some sentimental value with this car. It's my first car, purchased in 2006 with 50k miles. I've had it for 16 years and put 146k miles on it.

 
Rep Power: 222

My comments in bold:

Here's a list of what my car currently needs:
- Exhaust manifold/catalytic converter (current one is cracked and have the new one ready to install).
- Knock sensor (currently have code P0325 for knock sensor malfunction, new sensor arriving this week). What brand?
- Timing belt, water pump, tensioner (the current belt is 9 years old). - Priority #1
- Rear brakes - probably not needed, my 2000 still has the original brakes and I live in Canada

Overdue stuff that probably should be done:
- Spark plugs - check them, might be ok
- Fuel filter - skip
- Valve adjustment - check it but it might be ok
- Brake fluid flush - not really needed unless it's horrible
- Power steering fluid - not really needed unless it's horrible
- Coolant - you have to drain it, might as well put new stuff in
- New crank and cam seals, and oil pump o-ring good idea, think the oil pan has to come off for the pump o ring so new pan gasket as well, and new valve cover gasket + plug tube seals
- AC belt and power steering belt - they have to come off to do the timing belt and they're like $12, do them

Things I'm considering while I'm doing other things:
- New O2 sensors - it's doubtful you'll be able to remove the original ones and transfer them over make sure you only buy Denso sensors
- Clean fuel injectors - Skip
- New fuel pump assembly - Skip
- New coils - Skip

 
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Thanks for your comments.

The knock sensor I ordered is Standard Motor Products KS135. The reason I'm planning to do the rear brakes is that I'm getting some vibration on hard braking, and my front brakes are new. I get the same sound and vibration when I use the hand brake. I was planning to replace the valve cover gasket and plug seals during the timing belt job, as well as the oil pan gasket when doing the oil pump o-ring. I think I will attempt to remove the O2 sensors from the old manifold, and if I can't I will go ahead and order new Denso sensors.

 
Rep Power: 222

Good reasoning for the rear brakes,
Hopefully the car is ok with that knock sensor, they can be picky with sensors

 
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If the sensor doesn't get rid of the code, then I'll order one from hondapartsnow. I will be ordering some seals and o-rings from them anyways.

 
Rep Power: 367

the pain is that there are lots of stuff to remove before getting to the knock sensor. Not really sure if OEM is needed, but for the work, maybe getting OEM is better. Don't forget to tighten it (don't ask why i say it...)

 
Rep Power: 133

I can appreciate the indecision on your part. These maintenance items would closely reach the market value of your car.
Sounds like there is sentimental value (which can be dangerous haha) and you have already repaired brakes and suspension components. So if your wish to keep driving the car, your priority. as mentioned already, should be the timing belt service. This would include the tensioner, water pump, coolant flush, cam and crank seals, and accessory belts. Advice is to not unplug the crank sensor and to move out of the way - otherwise unplugging is prone to coolant leaking into connector and causing problems. Spark plugs are easy enough to replace as well and one of my favourite DIY jobs. Just use OEM NGK plugs. The manifold and cat will have to be replaced too.
Good luck on many more miles out of 'er.
My 2003 is still in the family with daughter #2 still driving it - it was well maintained as well and has proven still reliable.

 
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Thanks NDNV for sharing your thoughts.
I'm waiting on hondapartsnow for the new oil pump o-ring, cam seal, and crank seal, and then I should be ready to dig in. I'm also waiting for it to warm up a bit next week. It was in the teens here in Wisconsin all week and next week looks to be above freezing. I have a garage, but it's uninsulated and my propane heater only goes so far when it's really cold outside.

Question on the spark plugs. I looked up my make and model on the Denso website and ended up order some iridium plugs. The Honda service manual recommended Denso copper plugs or NGK copper plugs. Should I return the iridium plugs and just get the copper plugs recommended by the service manual?

Also, one other question I have as I've been thinking everything through has to do with supporting the engine while replacing the oil pump o-ring. To get the oil pump off I need to drop the oil pan, but I believe I need to remove the engine mount to access the timing covers to be able to remove the crank gear. So, I'm thinking that I need to support the engine under the oil pan with a jack until I get the crank gear off, and then temporarily reinstall the engine mount so that I can drop the pan and remove the oil pump. Would that be the best approach, or is there another way to support the engine while the oil pan is off?

 
Rep Power: 367

iridium ok

 
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You're wasting a bit of money with the iridium but it will be fine. As for the engine, you're only removing the one mount by the belts, there's still 3 other mounts holding everything up. It will droop down but it will fine. Or reinstall the mount before you pull the pan if you're that worried.

 
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Just thought I'd report back for anyone who might read this thread and wonder what I ended up doing. I replaced the timing belt, water pump, oil pump o-ring, lower oil seal, oil pan gasket, valve cover gasket, spark plugs, both accessory belts, knock sensor, and exhaust manifold/cat. I also adjusted the valves and replaced the coolant and power steering fluid. All the work took a long time to complete, but the car runs great. Thanks to everyone who commented.

 
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I'm coming into this thread a year later, and with the crazy prices on used cars, any maintenance is worth it. If you have the chance to do it, then do it. I bought my 03 EX Couple with 133K miles on it. At 153K I pulled the engine and trans to replace the input shaft bearing. While I had it out I did all the regular service (timing belt, water pump, front and rear seals, valve cover, etc.) My biggest regret was that I didn't know about that little $2 O-ring behind the oil pump, so I didn't replace it until two years later. Basically doing the work twice. But the car has 200K on it now and it runs great.
My point is that if you plan on keeping the car, and if you have doubts about anything, just replace it, if just for peace of mind. To me it's better to put a little money into it when needed than to have a monthly payment AND a repair bill if not under warranty.

 
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I suppose I should share an update. In March 2022 I ended up doing most of the work listed in the original post. The things I did not do include: O2 sensors, fuel filter, fuel pump assembly, clean fuel injectors, replace coils. After doing everything else, the car has been running great. Not a single problem or engine code since then. Up to 208,000 miles now, and still going strong. Thanks to all who posted in this thread.