Hey guys,
I have a 2003 Discovery SE, VIN SALTY16453A798XXX, and it recently failed a smog check. The emission levels were acceptable, however the “service engine soon” light was on, and it therefore failed. Live and learn, I though a “check engine” light was the bad one. I took the vehicle to a different service station, and had the ODD reset. I was advised to drive the vehicle 100 miles before having the smog re-inspection. Unfortunately, I didn’t discover this great site until after I had the ODD reset so we did not write down the code numbers. The “service engine soon” light stayed off for about 30 miles, and illuminated again. That was the happiest 30 miles of my life, by the way! The service technician was nice enough to re-read the codes for me again today, and they are as follows:
P0174- System too lean-Bank 1
P0171- System too lean- Bank 2
P0174- System too lean-Bank 1
P0171- System too lean- Bank 2
P0733- Gear 3 incorrect ratio
P0734- Gear 4 incorrect ratio
My research on this site leads me to believe I may need new O2 sensors, however the Gear Ratio has me stumped. The vehicle runs fine, and idles fine. It has 78,000 miles, and had a 60,000 mile (dealer) service and subsequent dealer services. At 75,000 miles, the vehicle had a problem. It would only idle, and died with any increase in RPM. I idled it for several minutes (O.K. quite a while…I also revved it trying to clear the fuel system.) It was towed to the dealer and the fuel pump replaced. That was not the problem, and after 5 hours of mechanic time and quite a bit of head scratching, I was informed that it was something in the air induction system that had dislodged. The LR was repaired, and got new spark plugs. The “service engine soon” light was illuminated when I picked it up, and the dealer told me it was to remind me that it needed a brake service. Hmmm.
O.K., that is the status, I hope I provided enough information, and thank you in advance for your comments and advice.

--Rob--

 

LR switched from a "check engine" light to a "service engine soon" light with the DII.
So they are the same thing just different names.

The SES light has nothing to do with the brakes, they lied to you about that one.
Take it back and have them clear the SES light, drive it for 100 miles and then have it re-tested.
You need a new MAF, but if they fixed it then the codes just need to be cleared so the light shuts off.
The light will NOT go out on its own, it MUST be cleared using a OBDII scanner.
You can buy one at Wal-Mart or on line and check the codes and turn the light off yourself.

 

Thanks for the reply Spike. I should have been a bit clearer. I had the SES light reset using the OBDII scanner about 150 miles ago (well after the problem at 75000 miles.) The SES light stayed off for approximately 30 miles, and then came on again. I have since driven the vehicle 120 miles. The codes provided were obtained yesterday and are therefore "current".

Thanks for the advice on the MAF. Is there anything else I should consider given the current OBDII codes?

 

no. just replace the MAF with a Bosch land rover specific MAF do not purchase one from Napa or Autozone aftermarket it won't work correctly.

 

The day I replaced my MAF (with similar codes) was the happiest day for my Discovery. I had no idea how much power I'd lost until the repair was done.

 

Thanks! I will replace the MAF and report back.

--Rob--

 

http://www.roverparts.com/Parts/MHK100800G.cfm

 

Advice taken. MAF ordered. Any installation tips? I assume I should also replace the air filter, reset the ODD codes, drive 100 miles without a SAS light and then re-smog.

 

it is the easiest install ever. just two or three jubilee clips need to be loosened. if you put a new air filter do not use the K&N air filter get a paper filter http://www.roverparts.com/Parts/ESR4238.cfm

 

Those are the most common codes when a MAF has failed.
Do not buy any new MAF unless it comes in a Rover box, some of the other Bosch MAF's may look the same but they will throw codes when installed.