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P1811C Transmission Code

2000 Buick Century with intermittent transmission surges while changing gears.

A local mechanic read the computer codes and determined a P1811C code but checked Step 11 of the AllDataPro readout.

Inspect transmission for the following:

* 203 accumulator piston seals rolled

* 2-3 accumulator piston and pin missing

* oil pump assembly damaged

* spacer plate and gaskets damaged

… etc.

P1811 is the Maximum Adjust and Long Shift code on Buick. What does the “C” add? And, does the Step 11 indicate actual internal damage?

I have been advised that there’s a gasket easily replaced on the side of the transmission with the Maximum Adjust code, but I’m wondering if this test indicates there’s internal damage and a total repair is needed. Thx.