Honda Civic VTEC Malfunction

civic
honda

#1

I have a Honda Civic EX 1.7L VETEC with 190K on it and almost running strong.

At 4,000 rpm it bogs down, bucks and looses acceleration. Code P1257 VTEC Malfunction gives me headaches. Honda garage cannot figure it out. They connected their diagnostic tool, took it for a ride and said it is hitting all the shift points and nothing else can be seen. But I still get the ‘check engine’ light. and same code. I’ve installed a brand new VTEC valve and experimented with oil levels from low to high to just right for the last year. Give the same P1257 code. Can you help?


#2

Model-Year ?

CSA


#3

It’s a 2002 Coupe EX. Man, how could I have fogotten that!?


#4

My guess is that common sense answer may be looking up technical service bulletins on the car (which he often does).

I am no expert on VTEC’s but there is not a tidal wave of ideas flowing out at you. So I figured I’d give you my thoughts based on general knowledge/reasoning (which will also bump the thread).

As I understand it the VTEC solenoid is basically a little oil pressure controller for an oil stream to the cam. Based on variable engine conditions the computer tells it what to do in terms of oil flow to vary the intake valve timing.

What you need to do is see the VTEC solenoid/valve not as “the part” that the code refers to but as one aspect of a system. I don’t know the precise details, but in order to function properly I can at least say that the solenoid needs reliable & properly functioning connection to the PCM (computer). It also needs a reliable & properly functioning oil supply. The solenoid itself may have been just fine. The problem can lie in something like a wiring problem to the solenoid or restrictions/clogs in the oil passages to the VTEC valve.

I also don’t know how the PCM monitors the function of the valve. This kind of info might, for example, come from a cam position sensor that the computer uses to monitor whether or not the valve is doing what it is telling it to do. This could also be involved in the problem. Perhaps the entire system is working properly but the computer has bad information about exactly what is going on.

Anyway, you’ll want to find out exactly what the Honda shop did in terms of diagnosis. If all they did was hook up a scanner & drive it around that’s not really adequate. At this point I’d say that someone needs an actual Honda factory service manual. It will provide a precise set of diagnostic steps to use for this code. If you have a garage that claims to be a “Honda” garage but they don’t have access to this info then I don’t know that I would trust them. You might be able to access this kind of info yourself through your public library and a source such as AllData. Sometimes you can get lucky and a dealership might even provide the info.

Best of luck with it.