have code P1491 & P0171 per the check at autozone. I have a 96 honda accord ex, 4cylinder, 4 door. I had a new fuel filter and pump put on ( as that was suggested) and also made sure the gas cap was on correctly and the check engine light is still on. Is there a sure way of knowing what needs to be replaced before I just start replacing things that don't need to be replaced? [align=right]
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since you've done the replacements have you cleared the codes to see if they came back? I believe a P1491 is an egr issue... do you have any sort of "stumble" or hesitation around 2500-3000 rpms? As for the P0171 do you by chance have an aftermarket intake or anything not stock on the vehicle?

 

P0171 = system too lean
P1491 = EGR valve lift insufficient

I don't know why a fuel PUMP was suggested... Seems pretty expensive to replace that just based on those codes. Did anybody measure your fuel pressure? Any other tests besides reading the codes?

 

The system to lean code can be caused by a vacuum leak or improperly installed aftermarket intake or not hooking up a MAF sensor if you have one... Anyway, just let us know the answers to those couple of questions and we'll get you straightened out in no time!

 

there is no stumble or hesitation, the fuel pressure has not been check, and the exhaust manifold had been replaced and is not a genuine honda part. What is a MAF sensor and where is that?

Thanks

 

MAF is a mass air flow sensor located somewhere on the intake if you have one.

 

and how do I know if I have one on the 96 Honda

 

Code p1491 is usually caused by a sticking egr valve. An egr valve sticking open can cause a code p0171.

 

So it sounds like an EGR valve problem. Here's a pic to help you out. I got this directly from our DIY section. 4th post from the top by deserthonda. It leads to an online manual. There are also online manuals available for downloading for free on your car. Just check out the DIY section.
By the way, your engine is an F22B1


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I had the P0171 and P0170 code and an aftermarket intake. I've had the intake for about a year though and no MAF. For some reason, after filling up my tank of gas the CEL light went away by itself.