Remember that this code is determined from a signal from the O2 sensor; so anything that makes the O2 see a rich or lean signal. This the reply I got because mine is doing the same thing right now:

Check for vacuum leaks, clean/replace air filter. If the engine is not noticeably rich (exhaust smell) then it's likely to be something like that.
When I drove my car back on a 11 hour trip after buying it, I had 232 code, the AFM intake screen was heavily blocked with air box silencing foam.
So, it's not just injectors etc you should look at.
By the way, reset the ECU after you think you've fixed the problem.

This is from Andrew on another forum.

Good luck with it and let us know how it works out

dave