I am getting the two codes P1171 with P1174. Whenever the MIL light turns on both these codes appear at the same time. I’ve been reading the threads about people with the same issue and some say that a trans code will usually pop up along with the other two. But I’m only getting the two. I took it to get looked at they said the cat was clogged but I’m not getting any symptoms of a clogged cat. Or a bad vacuum line. Anyone know what could fix these codes?
(2003 Land Rover discovery with about 230,000 miles

 

https://landroverforums.com/forum/di...1-p1174-75217/
read through this thread

 

Most of us do not memorize code meanings, suggest you post the Rave meanings along with the codes.

 

P1171 'Oxygen sensor system too lean fault banks A & B
Scanner not telling me meaning of other code

With a different scanner its giving me different meanings, Even when I put in Land rover for Manufacture specific trouble code.
it states "Additive Adaptive mixture correction TRA bank 1" and "Additive Adaptive mixture correction TRA bank 2"

 

That's why you get the code out of the rave manual.

Looks like you have a vacuum leak. What work was done recently?

 

I’ve added some fuel additives like Techron and some Lucas without much luck. I can’t afford to have a shop replace the parts as they quoted $6,000 for new cats. I looked up some of the symptoms for a vacuum leak and I’m not getting any of them. I know that you can test it with a smoke test and when I can borrow one I’ll try that. But im trying to fix it as cheaply as possible so I can pass emissions.

 

I would clear the codes, give it an itialian tune up and try to pass emissions. maybe throw in a bottle of techron. but if you want to fix it, you can build a cheap smoke tester with a cigar, the $8 pump from harbor freight at and rubber glove. My guess is at that age there is a vacuum leak somewhere.

 

@WoldD2 At 6000 for cats you are going to a shop that is lying sack. You can pickup a complete Y pipe with cats for about 700 plus shipping and about a hour to install 2 if there are some bad studs.

Tossing additives in will not fix the problem, I have had the 1174 it was a failing O2 in my case.

If you are going throw money at shops find a component shop.

But you are better off to learn some basic diagnostics, your truck is 20 years old it is in the grand scheme things simple.

Troubleshoot one thing at a time

• Start by getting a bluetooth OBD reader (amazon) and Torque for your phone.
• Setup to monitor your O2's and make sure they are responding correctly
• They may be a bit wonky if you have a vacuum leak
• You have a 2003 lots of vacuum lines - start with right (passenger) side of the intake manifold you have 2 lines there brake boost (big) SAI little.
• Remove the smaller line and cap the nipple temporarily - this will toss new codes that is fine. Clear your codes and drive around see if they come back it takes a bit.
• If code return you will need to check the brake booster line - that is a little more complicated

 

Thank you, I will look at it when I get the chance. I think it might be the air intake hose as I’m pretty sure it’s the original one the truck came with as it’s looking older and brittle. So it’s possible that it might have a crack in it someplace. I reset the ECU by taking out the battery and connecting both terminals for about 15 mins and it’s running better as of now. I looked at the cat after some driving and it wasn’t glowing red or having any smells like other people with clogged cats say.
it could also be bad 02’s when I looked at live data the voltage on upstream and downstream was staying static at 0.12 volts.

 

Per @Richard Gallant a torque app and elm327 bluetooth dongle would help a lot with diagnosis. Your codes are indicating lean. The ECU thinks it is lean on both banks due to the low voltage reading of the oxygen sensors. There are two possibilities, one is that it actually is lean and the 02s are working correctly, the other is that the 02s are defective. You can tell if they are completely dead at completely cold engine start as in first start of the day as the mixture goes very rich for just a few seconds at cold start and the 02 should read close to .8 volts even if it is running lean. If it does not, your 02s are completely dead. If they do, then you have a large vacuum leak. You can find excellent videos on how to make a smoke machine on youtube. You could also use the shop vac/leaf blower test - blow through the intake and soap everything looking for bubbles. Or use spray WD40 on and around the intake fittings and see if the idle speeds up.