Trying to determine if the Rover's ok to drive at highway speeds. It's a 2006 LR3 8 cyl with nearly 170k on it. Well cared for. New diff motor, water pump... whole stack of receipts.

Occasionally, the "Reduced Engine Performance" notification appears while driving and then turns itself off. Today, the check engine light came on along with "Reduced Engine Performance" and neither disappeared. Using the GAP II, I checked the faults and have what many consider to be normal for the LR3, most of which are Body Control related. None of the codes were or are Engine faults. I cleared all faults and five remained, listed below, all Body Control, plus one non-listed Parking Aid that should be a reverse sensor that's out.

B1B02-28 (2F) Low frequency coil
B1BA0-66 (2F) Excessive challenge requests or start attempt in storage mode (note: before clearing, this code was 6C, excessive challenge requests or start attempt in storage mode)
B1C57-14 (6C) Passive start ignition relay coil circuit
B1D12-15 (2E) Volumetric alarm power circuit
B1D13-15 (2E) Interior lamps 1 circuit

Before clearing the additional codes below were present.
U0155-87 (2C) Lost communication with instrument cluster control module
U0300-55 (6C) Internal controll module software incompatibility

There were also codes present in Audio System, Audio Amplifier, Cell Phone, Parking Aid and Ventilation. But nothing prior to clear or subsequent to within the Engine category. Nonetheless, "Reduced Engine Performance" and the check engine light both remain.

Now, something is up with the air suspension as it raises and lowers when stopped at lights every once in a while. This isn't a drive/no drive situation. But I'm concerned about the check light/note. Any thoughts?

 

The low frequency coil (I'm assuming thats the same thing as the rf interference coil) can prevent the ignition coils from firing properly and can even cause a no start - that could be it. It's located on the back of the passenger side valve cover area.

Unplug and see if the engine performance warning goes away. If so, get a new one, although the car will apparently drive fine without it - it just prevents radio frequency interference from the ignition system.

 

Thanks for posting what the codes are. I tend to not even respond to posts where people ONLY list codes, I am not looking up that stuff. LOL

The suggestion above of of the engine capacitor is worth looking into. Part number LR004160 . I will add: It's a small black "device" with three wires mounted to a metal bracket above the fuel rail. You have to remove the engine beauty cover to see it. Pic below of a new one install I found on the web. There are two styles though, the old ones are bigger. If you do disconnect it, I think you must jumper two of the three wires to get the engine to fire though. Its not required for the vehicle to run, but it reduces engine ignition noise which can mess with things like the radio and other systems. To jumper you connect both red wires, I think a red&white and red&brown. Third wire is black which is just ground but I do't think you have to connect it to anything.

I would also clean or replace the MAF but more importantly, clean the throttle body. You do not need to remove the TB itself, just the duct work then spray a cloth and carefully clean it. You have to manually open up the TB to get inside a bit. You also want to make sure the harness connector to the TB is secure and not broke. The locking tab easily breaks on them but without they typically hold on firm enough. Just verify.

 

That's interesting. Those two coil related codes are present on my 2005 and cannot be cleared. It runs like a top though...as well as it did the day I bought it in 2005. Also, the RF Capacitor was replaced for good measure just a few years ago. Not sure if that helps you, or what to make of it on my end, for that matter.