P1811 on Buick
On GM vehicles (Chevrolet, Buick, Saturn): maximum adapt and long shift
Severity: Inspect soon
GM bulletins tie P1811 to slips, flares, harsh shifts, launch shudder and a lit service lamp, so the transmission should be checked soon. We found no GM source on whether it is safe to keep driving.
It gets more serious if:
- Not verified: The transmission goes into limp-home mode (stuck in one gear, little power) or the vehicle will not move. Regulations require the light in limp-home mode, but we found no source saying whether you must stop
This page covers only what differs on Buick. For what P1811 means, the ranked causes and the test order, see the P1811 guide.
What's different on Buick
BuickYour car
1997–2002
Supported by vehicle dataGM 00-07-30-002B covers P1811 with slips and harsh shifts on Century, Regal, LeSabre, Park Avenue and other front-drive models. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
00-07-30-002BStatus unverified
Slips, harsh shifts, launch shudder or flares with P1811 or P0748
1997–2002century, regal, lesabre, park-avenue · issued · NHTSA 634985
Also covers Chevrolet Impala, Monte Carlo, Lumina and Venture and Pontiac and Oldsmobile models. Only the NHTSA flat-file summary was read, not the bulletin itself.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Sources and review
- GM 00-07-30-002B: slips, harsh shifts, shudder with P1811 or P0748
- GM PIP-4651: 4T45 soft or erratic shifts, P1811
- GM 04-07-30-020: Saturn L-Series service lamp with P1811 maximum adapt and long shifts
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error