New to this site. New to civics. NOT new to hondas. Anyone know of an easy DIY fix for the trouble codes p1166, p1167, p0401? I know its the O2 sensor and egr valve. I dont have alot of money to put into this car yet (97 Civic HX). It runs fine I just want the CEL to go away.

 

Clean out the EGR passages under the plate on top of the intake manifold. Usually the valve is OK but everything is crudded up so there's no flow.

 

Ok thanks. Am I needing a new O2 sensor? Or 2 of them? From what I can tell its just the first heated one, but 2 error codes? I have read other posts of people replacing 2 sensors from those codes

 

Get the EGR working first. The other codes may be resulting from it. The first O2 sensor on a HX is a special type that is expensive.

 

Ok thank you ill try that. One more thing.... there is a slight clicking sound when i frst start it up in the cold for about 20 seconds. Any ideas? Praying its not a rod

 

(depending on what you mean by clicking sound) ... Check the exhaust manifold for a crack, especially near the oxygen sensor hole.

 

Thanks for the help, i have an experienced civic owner comin up to help me take care of these issues tomorrow. If i have any more questions ill repost (hopefully not)

 

The other poster has a good point about checking for a cracked manifold, it is rather common.

Clattering noise from inside the top of the engine when it is cold could just be valve noise. These engines do not have hydraulic lifters, so the valve clearance needs to be adjusted periodically to compensate for wear.

The adjustment is done by taking the valve cover off and turning a screw at the end of each rocker arm. Be sure to read the official procedure and follow it exactly since improper adjustment will cause bad running and possible damage.

Even properly adjusted, a little valve noise may remain, it is nothing to worry about.

 

ended up just cleaning the valve, i had 4 error codes and after the cleaning only had 1. its still the o2 sensor, and my mechanic across the street said to do 5 drive cycles(warmed up then cool down) and that last code may go away