I've not had any personal expirience with this code, so take what I say with a gain of salt.

When you say limp home mode do you mean the trans is locked in 2nd and reverse only or that you lose power? LHM usually is in reference to the trans in which case you should also have trans codes.

The EGR and RF's both get gummed up on your engine and require cleaning periodically. Sticky flaps can cause a code.

There is also a transducer that operates the EGR valve. On my 606.962 (turbo) it is mounted on the firewall adjacent to the EGR. It may be the problem. Not certain if your engine has a second identical transducer that controls the resonance flaps or not. If so, the two can be swapped and you can determine if a) code disappears or b) a new code pops up for the RF's indicating the swapped transducer is bad.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)