'04 Disco 2, HSE 7, V8, 125k

This vehicle has been remarkably low maintenance for a Rover. I have done the standard stuff for a Rover with this many miles and have never had a major issue, until now. About a week ago out of the blue the misfires started and I have codes for just about every sensor there is. There are plenty of threads that address chasing this issue, but nobody has mentioned a symptom that I have.

Every, and I mean every, warning light flashes like crazy at odd intervals. When I start the engine, they all go totally nuts, then as it warms up they go into this random blinking mode, irrespective of what's going on with RPM's, etc. The most consistent is the battery light, I've checked the battery (it's fine), I've checked the alternator, it's fine.

So, far I have replaced all 4 O2 sensors, which got me 1/2 there, eg on misfiring on 2 now, it was 2 & 8 before. Replaced that MAF, which made a big difference on the intensity of the hesitations. Cleaned the throttle body, and replaced the air filter.

So, now I am getting circuit low codes for O2 sensors, MAF, Crank position, knock indicators, and am misfiring on 2, with crazy codes. The vehicle is totally drivable, has no problems with over-heating and seems to be running at about 90% efficiency.

Again, I have read all the threads on this and they have been very helpful. I'm hoping that someone can help me ID the issue associated with all the warning lights blinking and circuit low codes.

Next steps seem to be replacing some more sensors, checking vacuum lines, checking fuel pump, and looking for a faulty ECM.

Anyone seen this before? Any ideas?

Thanks!

 

If the battery and alternator are good is has to be your ECU or something with the harness. That's a totally odd situation. I'm subscribing.

Have you made sure that the ground strap behind the engine is tight and the ground to the front of the engine is tight?

 

Seafoam induction clean fixed my down stream O2 sensor codes. I still have 2 misses at idle but the O2 codes are gone. $6 fix...for now

 

I was dealing with the same issue this past week. I'd start oking for vacuum leaks. That was my first idea when mine started missing at idle and turned out to be correct.

 

Maybe replace the battery. Battery could have internal short
upon starting and the voltage goes too low and the ECU goes nuts
for awhile.

If your battery is 3 years old or older, don't cheap out.
Replace it now.
Low voltage causes all sorts of problems.


Check the fuse box main connector(s) to the fuse blocks.

Check the ground strap from the cylinder head to the firewall

 

I'm going to check the ground straps and vacuum lines this weekend and will post results. I'll run a can of seafoam through the tank and do the induction clean as well and see what happens.

Battery is relatively new and is high quality, but I may run by a shop and have them put a tester on it and see what we get. The real freak-out is on start-up so there may be something to the battery short scenario.

Thanks Guys!

 

There should be a ground strap attached to the driver side head and then the firewall. In front you'll see a black negative wire (thick) bolted to the block, just below the alternator, on the front, passenger side of the engine.

 

I had a few minutes during lunch today, so I opened the hood to take a look at the grounding wires, and wouldn't you know it, the driver's side was loose and shaking around. I removed it, cleaned the connections with some electical cleaner and re-attached it, the Mariachi band of warning lights has stopped!

Next step is to put the code reader on it and see if I can get some codes that tell me the real problem rather than a bunch of low voltage codes.

Thanks! This saved me a huge amount of diagnosis time.

Here is the grounding wire, just below the air intake on the driver's side.




Hardest part of this was finding the right socket for this crazy bolt. 11/32 was the closest fit, but still not quite tight enough to get it really snug.




Used some electrical cleaner to clean the connection while I was in there.

 

My ground connections are just as Charlie described. The socket for that valve cover bolt is 1/4 inch drive, 12 point 5/16 inch.

 

Sorry to jump your thread, but... Do all D2's have that ground on the rocker cover? I have a 1999 and I don't believe I have that one.