Usually this fault code is because of a failing fuel pump. The supply pressure is reduced and the ECU compensates by extending the injection pulse until it reaches it's limit. Have you replaced your original standard fuel pump with a Walbro item as in these detailed instructions Malcolm M3W?
https://www.mtwc.co.uk/wp-content/u...-pump-replacement-April-2020-update.pdf. If not I would suggest it is a good starting point as it will fail at some point in the not too distant future anyway. The original item is very unreliable. It is such a common replacement that Glenco Ltd. now produce a kit of parts for the M3W p/n ITP184.
You could check the fuel pressure at the test point on the RH injector, if it is less than 58 psi then this will confirm the problem is the fuel pump. Following the fuel pump replacement, it is a good idea to reset the adaptive maps using ProTune 2 as they will be compromised by the low fuel delivery pressure. You can only enter Advanced mode if you have an unlocked ECU but you should be able to reset the adaptive maps by disconnecting the battery for a few minutes if you cannot access it in Basic mode with a locked ECU. The front cylinder is the LH (Port) one, or RH if you are looking at it stood in front.
