Ok so I have an odd issue here.

While driving the Service Engine Soon light flicks on and off with a MAF and Engine Temperature "ERR" reading. Both say "ERR" (error) and stop collecting data. Yet the Rover runs 100% normal. No codes. Unplug + Replug the Ultra Gauge and it runs perfectly normal. 10 miles down the road later it will do the same thing - SES light flicks on, Ultra Gauge shows ERR readings. Vehicle continues to run normal.

Replaced Crank Position Sensor with a BOSCH because the entire car (engine and electric) was just randomly shutting off/dying while driving. That fixed the problem. Now this. Anyone ever seen this before ?

 

When you say engine temp do you mean coolant temp or intake air temp? Because the maf also has the IAT sensor in it. It's strange that there are no codes with the SES light but I would recon that the MAF is going bad.

 

I had pretty much the same thing happen when my CKPS was going bad, but I didn't notice a flickering SES light. I changed the CKPS and the Ultragauge "Err" symptom went away. At the time, I didn't have any MAF data points in my ultragauge screen, but the "Err" was showing up for the coolant temp - truck ran completely normally.

I wonder if you got a bad CKPS. You might have already seen my thread on this - here's a link.

 

I've had my Ultragauge drop out and show ERR readings when my battery was low.

 

I recently had the ERR message on my Ultragauge. Pretty sure it was due to my MAF.

I had managed to get a lot of water into the airbox and pretty sure that killed the MAF.

Drained and dried things. Replaced the MAF and all is normal now.

 

Yeah, I was gonna say a bad MAF or a bad temp sensor would do that. Unplug the MAF and see how it runs. The ECU defaults to a speed density system where it uses the TPS sensor and rpm to determine fueling. If the codes go away then you probably have a bad maf. The other way to diagnose is to chart the MAF sensor using the torque app.