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Hi Fellow Members,

2001 civic EX, 179.000 miles. original owner. Upon gentle acceleration or just keeping up a steady cruising speed, say, 40 mph, car hesitates/stumbles slightly to the extent you can feel it. Thing is so far there is no check engine light illuminated to assist in determining the cause. I know that sometimes the computer will set a code but not illuminate the check engine light (right??). If so, please advise and I will check for codes (cant do it just today, but will asap if necessary).

Meanwhile, one question I have is : What symptoms can this car have and it NOT be connected to a sensor that would throw a code? Bad /clogged fuel pump? Bad coil pack? Bad wires supplying coil packs? Bad/dirty air filter?

Thanks, people.

 
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Check for codes, might be a slightly clogged cat, maybe a lazy a/f sensor

 
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Thanks, Colin. What is an af sensor? Also, do you know if the fuel filter is connected to the computer such as to trip a code if it is clogged?
And if it may be bad coil pack towers do you know what the resistivity in ohms should be for them? Thanks.

 
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A/f sensor is your primary o2 sensor. Car isn't smart enough to have codes for the filter. It's just the sock in the tank. No idea what the xoil pack resistance should be

 
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Colin (or other members), I pulled a code 45, (SRS light blinking 4 times fast, the 5 times slow, NOT the blinking of the check engine light). Also known as P0780 according to this site linked below. BUT other sites say cod 45 has to do with fuel system (O2 sensor/EGR/MAP sensor). How confusing Which is the right code diagnosis?

https://www.google.com/search?q=hond...t=gws-wiz-serp

Should I proceed to gamble to try to replace a solenoid? Never did that before. Are there more than 1 solenoid? The article also mentions that it could be other things other than the solenoid, I think.
Thanks.

 
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Get an actual scanner, they're like $20

 
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So weird, AZ and Adv Auto both found nothing wrong with my system, no codes stored anywhere, using their $1,000,000 computer scanners. I guess thats good news. Anyway, thanks for your support, Colin.

 
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The o2 sensor won't always throw a code. Quick check for a clogged cat would be to loosen the manifold bolts at the head a little and see if it runs better. Obviously it will be louder

 
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Right- also, easy to do, change plugs. O2 sensors are also cheap/easy. Thanks, Colin.

 
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Make sure you buy the correct ngk plugs and denso o2 sensor. Rockauto has both

 
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Is there only the downstream O2 sensor? Or are there 2 sensors? If 2, should I replace BOTH?

 
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No the upstream one is the one you need. It's what measures the air fuel ratio

 
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Pippo, did you ever figure out the issue? I am having the same problem with my 05 civic. https://www.civicforums.com/forums/3...ml#post4816587