Contour Enthusiasts Group Archives Forums Modifications Zetec Maintenance CEL code P0171 - could it be the spark plugs?

I've had my Check engine light on for a couple of months. I took it to the dealer and was told that it was code P0171 - System Too Lean - Bank No. 1 (and charged ~$150 - what a rip off!).

Dealer suggested replacing MAF sensor and O2 sensors and wanted ~$600 for this (of which $50 was for "resetting the computer"). I could tell that I was being taken for a ride so I decided to search the web which lead me to the CEG. At least some good came of my $150 scan

After searching the archives I tried cleaning the MAF sensor with electronics cleaner, changing the air filter, and re-setting the computer by pulling the fuses but the CEL came back on. I haven't touched the Oxygen sensors yet as I don't know what that involves or if I can do it myself.

Is it possible that this code could be caused by worn/old spark plugs? I got the car used and I doubt the plugs have ever been changed. The car is at 100K miles and I know that plugs are recommended to be changed at 60K for the 4 cyl.

Other than the CEL light being on and the 1-2-bang-shift the car runs fine. I'm getting 28 to 29 MPG highway and 25 MPG mixed highway and city. Since the engine is humming along, I don't want to mess with the plugs unless there some benefit - such as addressing the CEL and/or preventing the catalytic converter from being ruined/poisoned. Thanks

1-2 bang shift, try a TSS. Not easy to put in if the car is northern, tends to corrode in. Plugs should be changed with the appropriate double platinum type, by now your plug gaps will be too wide. Take one out carefully and take a look. Caution: aluminum head. If it looks good and gap OK, you probably don't need plugs. Try this topic for P0171: P0171 ZetecSearch P0171 Zetec Maintenance all posts. Vacuum leaks are cheap to fix, harder to find. Look for cracked or unplugged hoses.

I had the same problem.
I did what you did but also relaced the upper O2 sensor before the cat. This was cheap--roughly a $40.00 part at autozone. The light never came back on.

My contour was running lean also. I changed the O2 sensor. IT ran me $90USD. Trust me you want to get that fixed fast. Running lean can cause BIGGER problems down the road. It can cause piston problems cause there isnt enough fuel to be compressed that can lead to engine knocks.

P0171


That fugging code haunted me in the past..

In my case was MAF... friggin K&N oil was all over the MAF.. once cleaned no more codes.

Usually I get a lean code when it's time for me to clean my MAF, but being winter I reckon, I got a rich code (0171). Cleaned my air filter and MAF and was good to go.