Codes before purchase
P16CF(00)
(ECU: 7EB)
Status: Test failed since last DTC clear
P131E(00)
(ECU: 708)
Status: Test failed since last DTC clear
P15FF(00)
(ECU: 7E8)
Status: Test failed since last DTC clear
P109A(00)
(ECU: 7EB)
Status: Confirmed, Test failed since last DTC clear
Codes read with other than a STAR reader can be dubious and inconclusive.
A reliable combination for the R350 is the M276 engine and 7G-Tronic transmission. Later model years have the M276, which replaced the M272.
The V8 M113 and M273 versions seem not-too-unreliable.
My Audi vag-com can do generic obd but it won't connect to the R.
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Supporters of M-B diesels are quick to mention "it's not the engine". Technically this is correct. There is nothing fundamentally flawed with the compression ignition cycle. The unreliable bits are mainly with hardware attached to the engine. Nevertheless, the problematic hardware has a 1:1 correlation with the OM642 of certain model years.
Search specifically for these keywords:
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These are the main concerns I found with the W251 OM642:
- "Black death". Realistically a reasonably easy DIY.
- Transmission "Conductor Plate Sensor". Again easy.
- DPF/EGR/swirl motor. That;s the big one. If they give me too many headaches I can get a tune which deletes those.
- Air suspension. I dealt with the Audi C5 allroad. Easy fix and they can be replaced with Grand Cherokee non air parts.
- Floor control modules water damage from water leaks. This can be a bad one. I am very careful to check for a musty smell and other sings of leaks.
My biggest concern is with it's suspension, I find them too soft. I really feel I would like a much bigger sway bars and stiffer suspension all around, without dropping height. It does not look like there's anything for the W251. I found some stiffer sway bars for the grand cherokee, I wonder if those are compatible.
I found an AMG R350 with airmatic suspension. I am wondering if it's worth the hassle. How much ground clearance can be gained over the regular R? Does the Adaptive Damping System offer considerably better handling?









