Recently these codes have been occuring on my wifes discovery. Just a little back ground. Replaced plugs, wires and coils at the dealer past six months. Recently the flywheel sensor was replaced at the dealer after vehicle stranded my wife.

The check engine light recently returned with the P0301 cylinder #1 misfire and the P1412 which indicated the left side SAI valve was the culprit. Went to the dealer and replaced the vacuum harnes and was told the harnesses tend to fail since the vehicle has 109 K on it. Replaced the vacuum harness and the vehicle appeared to be running much smoother. Cleared the faults in about 50 miles the fault returned this time indicating P1414 and again P0301. I shared this with dealer and they said that most likely the solenoid is faulty and not the SAI control valve. They stated that they have not ordered one of these valves in 14 months and there were known in their system. I was told that this valve is used on Volvo's. I hate to invest $200 dollars to replace the solenoid by just guessing.

Can someone advise as how to best trouble shoot and also will this clear up P0301 and misfire?

 

1412 could also involve front O2 sensor. 1414 is a bad test result when system is "prompting" the SAI system to work and checking to see that it is indeed making a change. See attached.

However, it might seem strange that a code is created for a test of the system, but not a code for system being off-normal under normal operation for a few drive cycles.

 

Land Rover Parts & Rover Accessories From Atlantic British | Discovery, Range Rover, LR3, LR2, Defender, Freelander and Land Rover Series Parts & Accessories

 

Did the dealer do the tune up and coil, if so you have a 1 year warranty from them which will take care of that 301, #1 cylinder, misfire.