Hey Folks,

I have a 2004 Discovery II SE. I'm wondering if anyone has some suggestions with regard to the following codes that are popping up recently.

Recently I pulled the front drive shaft to replace the U-Joints, but when I took down the street to verify that was my problem after removing it, I started having other issues as noted below. Also, just prior to starting work on the U-Joints, I did notice that while stopped, the idle started to drop and it felt as if the engine wanted to die.

P0101 - Mass Air Flow Sensor Signal Error Fault
P0301 - Misfire Cylinder 1
P0303 - Misfire Cylinder 3
P0305 - Misfire Cylinder 5
P0307 - MIsfire Cylinder 7
P1415 - SAI Bank 1
P0135 - 02 Sensor Heater Circuit Malfunction Bank 1 Sensor 1
P0300 - Misfire on Multiple Cylinder


The work that has been done since I purchased the vehicle in 2012 is listed below:

The following items were done in 2013 - 2014

Replaced engine due to cracked cylinder lining.
Head Gaskets were done prior to the "new-used" engine being installed.
New plugs, wires, and coil.

2015
New Power Steering Pump

The rest was done within the past year.
New MAF
New CPS
New Banks 1&2 O2 Sensors

So, that said, does anyone have any suggestions of what might cause all of these issues to seemingly pop up all at once?

Note - I wanted to double check the codes this morning before posting in the forum, but found I had cleared them after I had initially written them down. After starting it to see what would pop back up at idle I only got one code for a misfire in Cylinder 7.

Thanks in advance for your help.

 

Replace the Bank 1 pre-cat O2 sensor, even though you replaced it only last year. Sometimes they last years, sometimes months, sometimes weeks and sometimes they are bad out of the box. Buy the Bosch 15175. The only thing I know of that can cause misfires all on one bank are the O2s.

 

Thanks, this is where my head has been also. I wanted to get some additional opinions before I start throwing money at it.

 

Which side of the engine was cracked? I ask because the other thing that could cause an entire side to act up is a clogged catalytic converter.

 

Good thinking Charlie! That would also back-feed pressure into the SAI system. Which may explain the code for that as well. One thing you can do is, take the upstream o2 sensor out of the exhaust on bank one. That will give the exhaust pressure somewhere to go. Then see if it runs better. Just pay attention to where the hole is pointing! You don't want to burn anything up.
That can also mess up your MAF sensor readings too.

 

I had the same problem on another vehicle and the dealership, of course, said I needed a new engine (15000 dollars). I said no thanks and llimped home. Parting words from service manager? "You'll be back in a week." A-hole. I unbolted the exhaust and it ran perfectly. A long screwdriver took care of the clogged cat (later replaced) and, six years later, it still runs fine on the same engine.

Anyway, that COULD be the problem.

I know nothing about SAI except that it is for emissions at startup. And that the components are always in the way. And that they are expensive to replace.

 

SAI just comes on briefly when the engine is below a certain temp. It's just to heat up the cats and get it into closed loop faster.
$15,000!!! You could buy several more Rovers with that kind of money! Of course they'll all need new engines... LOL!

 

FYI on the SAI.
There are fault finding/tests for SAI in manual you can download pdfs for free.
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