P1171 & P1174 Codes
 

I've got an 03 Disco that I just had the plugs & wires replaced, as well as the front passenger O2 sensor. Prior to replacing these items the SES light was constantly on and was actually flashing for about a week prior to having work done. The fault codes were cleared after the work and my Disco was running like new again. Roughly 2 days later the SES light returned but with no flashing. I changed the fuel cap which was recommended and, what do you know?!?! The light went off immediately the very nexttime I started it up. About 3 days later, the light returned and it's been on for almost a month now. WTF??? I'm reading all sorts of threads on here about it and it doesn't seem to be clear what those fault codes mean. I know that the descriptions are System too lean (Bank 1) Additive injector adaptive fueling, lean limit exceeded LH bank & System too lean (Bank B) Additive injector adaptive fueling,lean limit exceeded RH bank.....anyhelp would greatly appreciated......emissions are due :(

RE: P1171 & P1174 Codes
 

How many miles? Check connections on the replaced sensor, and the sensors should all be replaced at the same time. They wear out around 80K to 100K. You have an O2 sensor problem, and it is probably due to having one new and the rest old.

Buy a cheap code reader at harbor freight for $29 and reset the codes just before you have the emissions test. It takes just the right drive cycle to set the code off and just the right one to make the light turn off again.


Never never never never never drive your truck with the light flashing. That means shut it off. I carry a scanner in the truck to check when the light comes on. I had bad cats and worked through wiring issues, and now it is just habit.

OK....I've changed ALL FOUR 02 sensors, had all the codes cleared and drove about 200 miles and the pretty little SES light came back on. Just pulled the codes again and it's still giving me P1171 & P1174. Anyone else have any suggestions? I was thinking MAF meter but I think that would give a different code.....not 100% sure of that though. Possibly an intake manifold gasket issue?

Looks like a MAF starting to fail but don't do anything just yet.
Have you done a vacuum leak test, especially from the air filter box to the t/body and the manifold?

these codes mean that youre running lean, and too lean for your injectors to compensate, theyre staying open as much as they can, and youre still getting too much o2 in your exahust. does your car have an exhaust leak? do like mike said and check for intake leaks. dod you remove the upper intake when you did the wires? it could be a mafs, but dont guess at that, its too pricey for a guess when it could be a lot of other things.... bad gas, low pressure, cracked intake tube, is the air cleaner lid on correctly

I don't know if it will help, but i had DI with similar problem. we put it on a comp. and same deal, to lean on both banks. I took of MAF sensor and cleaned it (i know your prob. not supposed to do that) and the problem went away. I have since drove the vehicle ~3500 miles. If I am way off base please say so.

If I conclude that is my MAF going bad Im goin to clean it.... carefully

D1's MAF's can be cleaned, when done correctly and while using only an automotive MAF cleaner, where a D2 can't.

The shop that I had replace my coils and wires told me that the intake manifold gasket didn't need to be replaced because it was a metal gasket :( I took his word for it because I work at a BMW dealer and our gaskets are the same way. I would've rather had him just replace it because it was already apart. Sounds like that may be the problem? I'm going to swap the MAF with one that we stock for a BMW X5 4.6 and see if that cures it. If not, it'll be going back to the shop for an intake gasket. I do have a slight exhaust leak where the exhaust manifold downpipe meets the cat on the passenger side. I've replaced the gasket like 3 times and the nuts always seem to work their way lose after 3 months or so. Is that something that I can just put threadlock on and be done with it?

Hey, Mike. What's the reasoning behind this? I've got a '99 D2 and I used cleaner on it just fine. Problem solved...for like the past couple of months. I know it's just a crutch, but it seems to be working fine so far.
-C.