Where we're your two leaks? Did your codes return?

 

The first thing I would do is take a good look at scan data. How do the fuel trims look? O2 sensors? Are they really working, or are the O2 sensors lying?It's somewhat rare, but they can get stuck with a rich or lean reading and send your fuel trims out of control. Which can either drive the system rich or lean for no reason.
The MAF data can also help you determine if it's good and working properly. You should have at least somewhat of a spike right at the start of a snap throttle. If you don't see a defined spike in the reading after a couple throttle snap attempts, then I would clean it.
Also, if the MAF is dirty, it will appear lean at idle and will jump rich at WOT.

 

I am getting the P0174 error code also and it says "System to lean Bank 2"
Can this be caused by a leak or should I replace 02 sensor?

 

You are running way rich.


Engine Code: P0171

Inspect the MAF.
Change the air filter.

Check the rubber after the MAF and take it all apart and inspect the rubber.
Put it back together with good tight fit.

Inspect for vacuum leaks - Power brake - inspect.
Vacuum line going to Air Injection at engine start - inspect.

Do not CLEAN the maf unless you use sensor spray from CRC or such.
and the Truck has to be OFF to clean the MAF.

you may need a new MAF if cleaning it does not work.





Land Rover Engine Code: P0171 = System too rich (bank 1) Multiplication injector adaptive fuelling - rich limit exceeded LH bank.

Click to Process more Land Rover Engine Codes here


Engine Code: P0174

Land Rover Engine Code: P0174 = System too rich (bank 2) Multiplication injector adaptive fuelling - rich limit exceeded RH bank.

Click to Process more Land Rover Engine Codes here

Use http://enginecodemaster.com

 

I've gotten lost on who has what issue but for vacuum leak if you eliminate the easy sources, I have had success replacing the upper intake gasket and injector o rings. DiscoMike can comment to a certainty on this but any time I have had to remove my upper intake and not also replaced the plenum gasket, I had a leak. It is a single use gasket in my book. Also, if the fuel rail is jostled or removed, I have always had a problem with the injector o rings leaking. Both of these can register as a vaccuum leak and the latter can even drip gas on top of your hot engine. Bottom line is that if you eliminate the hoses and other sources of vac leak that you can easily reach, and you pull the intake, spending a few bucks and a few minutes replacing the injector o rings and plenum gasket save you IMMEDIATELY needing all of those things again.

But I am a monkey with a stick in the presence of Dusty, DiscoMike and some of the other commenters so if they contradict me, I agree with them.

 

Not sure if I should start a new Thread or can I ask two questions on this one? I have a Disco 2 V8 4 liter LHD Auto (brought in Sweden) I am getting the codes P0171 and P0174 on my ODBlink scanner. What I have found is there is a slight Whine but I suspect that it might be a Idler or could it be a leak? MAF operation is fine. So I looked at the fuel trims and O2 sensor operation, I am getting very high Long term fuel trim. Voltage reading on O2 sensor Bank 1/2 sensor 1 is 0.45/0.55 and the strange thing is I get a 1.12V reading on O2 sensor bank 1/2 sensor 2? Now there are only two sensors installed and they are in the pre catalytic convertor position, the exhaust only has the option for two sensors to be installed, also the exhaust looks to be the original! Anybody got any ideas?

 

In case you were wondering, I had a P0171 and a P0174 on my 03 Disco, at first, and here's how I fixed it:

I would clear the code with my bluetooth OBD2 scanner, and it would go away for a few days, then return again. After a few weeks, I would start getting a THIRD code, that I forget the number, but the description was "Gear 4 Incorrect Ratio".

Fix was $40, here's how:


I purchased that MAF sensor. When I received it in the mail, I found the housing was far too small to fit on my Discovery.

1. I used a 6-star TORX bit to remove the sensor from the newly purchased Chinese MAF
2. I used a 5-star security bit to remove the stock sensor from the old, failing MAF. IMPORTANT NOTE the 5-star bit was tough for me to find. I ended up going to a NAPA warehouse and finding one there for about $4. The correct size is T-25.
3. Switched out the old sensor with the new sensor, plugged it back in, and it works! I also used the 6-star screws when screwing it back in, because of how much more common they are. Stupid over-engineered Rovers

This was a simple, 10 minute job (despite the 3 hours I spent looking for the security bit) and it fixed my issue for $40, as opposed to buying an OEM Bosch MAF, which would have cost upwards of $100!!!

Edit If you have the error codes, don't immediately assume it's a MAF!!! It seems like vacuum leaks and injector seals are prevalent causes for this code pair. If you have some extra cash to spend, it might pay off just for the extra security and to ensure it's not the MAF, but if you don't want to install it make sure it's not those two problems either!!!

 

171 and 174 for me are usually vacuum leaks. If just one and not the other, is usually on one bank and always an injector seal. They get old and brittle from heat, do them all if you pull the rail. If both, usually the metal gasket, hoses, or hose connections as it leans out both sides and that often happens above the lower manifold unless it's multiple injectors.

I've not had a bad O2 sensor cause the DTC since they are sensing the lean condition by responding to a greater amount of oxygen in the exhaust. It's not impossible, but would be lower on my list, with vacuum leak first, MAF second.

A high trim would confirm the ECU is pushing the upper limits of the mapping in order to richen the mixture as it tries to overcome the lean condition.

 

I too am getting those codes. After redoing the whole top end gaskets and seals to include the injector seals and back the codes came after 2000 miles. Bought the chinese MAF sensor and will install it once it gets here and see what happpens. I got it $26.25 shipped.

 

Well, it seemed like I got some extra power from the new maf. Codes came back though. I also inherited some cold start stumble. Gonna put the old maf back and see if the stumble was the new maf. At least I dont really need to sort the check light until 2017 when my next smog check is. Gonna do the redneck smoke test using a cigarette and a plastic soda bottle and see if I can pinpoint the vac leak.