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Old 11-17-2020, 10:30 PM
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Join Date: Jun 2000
Location: Saugus, CA USA
Posts: 2,042
Impermissible Ratio with a 722.6

My wife has a 2000 C280 with 216,000 miles on it. We had the codes read for other issues and it showed impermissible ratio, although it doesn't seem like it has mechanical issues (no slipping). Is this just showing it's age and still has a bunch of life left or is it the beginning of the end? The car needs money for the other things and I was wondering if I should spend the money fixing them or sell it. Replacing the transmission would not be worth it. Generally speaking, what's the life expectancy of them? I'm used to standard transmissions, not much experience with slush boxes.


5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)
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Old 11-17-2020, 11:32 PM
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Join Date: Oct 2004
Posts: 4,034
Most often that code shows up when the trans is low on fluid. I'd initially want to know the fluid level and fluid condition. Assuming both ok, I'd see what the adaptations look like to make sure that one of the clutch packs hasn't maxed out. Lastly a check for fluid contamination of the TCM, potentially screwing with a speed sensor reading.

90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE
Milled & ported head, 10.3:1 compression
197 intake cam w/20 advancer
4 ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff
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Old 11-18-2020, 03:33 AM
Registered User
Join Date: Jun 2000
Location: Saugus, CA USA
Posts: 2,042
It's got a transmission oil leak so I checked the level and it's ok. It's due for a transmission oil change. The other problem it had is the conductor plate is occasionally telling the transmission controller not to go into gear. And then the throttle body actuator is occasionally not actuating, hence the debate whether to fix it or sell it.
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Old 11-18-2020, 10:21 PM
Registered User
Join Date: Sep 2004
Location: Seattle
Posts: 1,971
The conductor plate and connector are a known issue so I would replace that. I don't think it is super hard to do, although I never did one myself. There are several videos on YouTube showing the process. Mine is still going strong at 360,000+ miles with the new owner.

1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra
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