[capt_slow]

A few days ago, in the Costco parking lot, my i3 threw a check engine light and a "Drivetrain: Drive Moderately" fault indicating electric drive only and REX was unavailable. I restarted the car and fault went away, but check engine light remained.

Scanned the car with ISTA and it came back with this...

REME 21DD1B internal fault (rotor position sensor)

Fault Description: The diagnosis monitors the configuration of the rotor position sensor for plausibility.

The fault is detected when the configuration data in the control unit does not match with that of the
rotor position sensor.

Measure in service: Replace REME

Perceptible effect on customer:
US: Malfunction indicator lamp
Check Control message (570): Trip can be continued. Drive.
Functional limitation
The following functions are not available:

• Start Range Extender
• Charging the high-voltage battery

Cleared all faults in ISTA, check engine light gone, and car drove normally for the next 5 days on both battery and REX. On the 6th day, the same fault came back in the middle of the night while charging at home. ISTA showed it was not only the same fault, but it actually occurred during the last full charging session the night after the first occurrence. A total of 3 occurrences.

Even though my car is well within the CARB warranty and the REME is covered, I'd like to see what everyone's experiences is with this fault. Is it really the REME or does it imply a problem with the sensor itself?

[capt_slow]

A few days before the car was suppsoed to head to the dealer, I rescanned the car in ISTA and the 21DD1B fault disappeared.

It's wasnt even a stored inactive fault. Nada. Nothing. Zilch. My guess is this fault had a healing counter that hit the criteria that cleared the fault from memory.

Since I no longer have a fault code for the dealer to see, I'm going to continue as normal until it shows up again.

[capt_slow]

Was charging at a public L2 station the other day. After I stopped charging, unplugged, and started the i3 back up, got this error:



Restart the car and message went away, Rex fired up fine on the trip home. Had a feeling it was the same code. Sure enough it was the same 21DD1B fault in REME when I scanned it in ISTA that evening. The fault even preserved the occurrences from my OP. Will try to get a dealer visit in ASAP before the code goes away.

[capt_slow]

It really was a PITA to get this fixed and not the way you think. Because the fault disappears, there is a narrow window where you need to bring it to the dealer. Otherwise, they wont be able to do anything and you'll be out of the diagnostic fee.

Once the fault popped up, I parked the car and never moved it again till it was time to go to the dealer.

That said, it's fixed. Got the REME replaced under the 15/150 CARB warranty. Entire rear end had to come off in addition to some of the bits in the engine compartment. They drained the refilled the coolant as well. Entire job would have cost around $8K out of warranty.

Car was also reflashed to the latest I-Level, which for the i3 is I001-24-11-520. Surprising there is no newer release.

[Mondomensch]

Originally Posted by capt_slow

Car was also reflashed to the latest I-Level, which for the i3 is I001-24-11-520. Surprising there is no newer release.

Thanks for the updates!

My interpretation is that the “24-11” part refers to Nov 2024, and if issued once a year for our now out of production i3, the next one wouldn’t show up for another 6 months.