Hi folks,

I replaced my oxygen sensors yesterday based on codes and now am getting a PO171 and PO174 lean. I recently replaced my MAF as well.

Can someone give me some idea on what to check? Does this not mean there is some sort of leak between the engine and the sensors (I don't hear or feel one, but that's not dispositive, I guess).

2000 Disco II with 118K.

Thanks!

Charlie V

 

Could be a vacuum leak somewhere. Have a good look over all the hoses. Carefully spraying some carb cleaner can also help find vac leaks. (rpm changes with engine running as cleaner is sucked through leak spot)

What were the original codes you were having before replacing the maf/oxygen sensors?
Also, did you use aftermarket "universal" type sensors or were they D2 specific.

 

Both heads are running lean.
In this weather, never use carb cleaner to find a leak or you will be looking for a fire hose. Might try water if anything.
When you installed the 02's, did you make sure both the connections were oil free?

 

I should probably check the connectors because I am not sure they were oil free. I was getting the whole list of codes, such as gear ratio, O2, lean, cylinder misfire. Most cleared up when I replaced the MAF and passenger side O2. The drivers side O2 arrived separately. I cleared all codes and the lean bank codes were the only ones that popped up. I do hear a faint exhaust leak until it heats up and I am sure it is from the manifold flange (to the pipe) because I have had a lot of trouble with the studs and nuts on both. Is that a likely cause?

 

Mine were caused by an intake leak. The clamp on the intake hose if the throttle body was not in the right spot and was not tight enough. I moved the clamp all the way to the end of the hose, it was about 1/4" from the end and I tightened it with a nut driver. I couldn't get it tight with a screwdriver because the slot was messed up.

 

I guess I will start at the filter and move my way back

 

Start with the exhaust leak first especially it it is before the 02's. That sort of a leak will throw you lean.
Air filter won't cause those codes but might want to check and replace it if dirty.

 

I had the same codes for ever and finally fix it. First fix that exhaust leak than contact me and I will tell you how to easily smoke test your vehicle using a cigar. U will be amazed to see all the vacuum leaks which is usually the cause of these codes in our Landy's.

 

Will do. I'm going to work on it this weekend. I want a solid week without an SES light. ALOT to ask for!

 

Fixed the small exhaust leak. Ready for the cigar test instructions. I'm still getting the codes.