Error Code P1811 is defined as Maximum Adaptive & Long Term Shift.
This error code is a manufacturer-specific trouble code, meaning it does not apply to all cars makes. Rather, it applies only to specific 2002 Land Rover Discovery II makes, such as Buick, Chevrolet, GM, Pontiac, etc. Specification of the definition, troubleshooting, and repairs still vary from one make and model to another.
As the engine run with the adaptable shit occurred, the PCM (powertrain control module, also known as ECM or engine control module in other 2002 Land Rover Discovery II makes) identifies throughout the following conditions happened twice per trip: Condition 1: 1-2 Shift over 0.65 seconds, and 1-2 Shift adaptive reaches its limit. Case 2: 2-3 Shift over 0.65 seconds and 2-3 Shift adaptive reaches its limit. Case 3: 3-4 Shift over 0.65 seconds and 3-4 Shift adaptive reaches its limit.
If the shift from one gear into another other than reverse and forward engagement takes more than 0.65 seconds to complete, then the Error Code P1811 will be set. The PCM will command the maximum line pressure inside the transmission, which results in harsh shifting. The PCM will also activate the Check Engine light and set the code simultaneously.
In many cases, the PCM will sense a slip and will increase the line pressure to maximum to prevent the transmission from further damage.
As with other error codes, this code activates the Check Engine light and registers the code to your 2002 Land Rover Discovery II ’s memory system. Other symptoms include:
Cycling the key on and off may remedy the harsh shifting until the criteria for the code is met at once.
Many problems result in the activations of this code, namely:
Many makes such as GM, has released a technical bulletin to diagnose this code properly.
Note that, due to the transmission’s orientation, and how it sits in a 2002 Land Rover Discovery II , diagnosing this code will require a little bit of work to access the pressure control solenoid and the valve body.
A mechanical problem in PCS is usually caused by contamination in the valve body or wrong fluid level. Thus, these are the first ones you need to check.
Also, note that this code means a slip of 6.5 seconds or longer. Thus, there may be other reasons for this that you need to check, such as:
If you have a mileage less of than 100K, then you may replace the pressure control solenoid and valve body.
For other causes, such as burnt clutch pack, worn accumulators, or a tripped overdrive clutch hub, then that would need disassembly and repair of the transmission. Repair for the transmission doesn’t always mean overhauling it though. In many cases, it simply means replacing the solenoid.
A popular quick remedy you can use before driving into extensive labor and expensive repair is to install a shift improver kit. These kits come with new set of accumulator spring and spacers to limit the travel of accumulator piston, which would speed up the time it takes to apply the clutch.