Originally Posted by RBob

This is a knock detection system error. It can be caused by a number of items. Which item can be narrowed down by when the SES lights up for that code. It it happens shortly after starting the engine then the knock module or wiring to/from the module, ECM, and power may be the issue.

If the SES lights shortly after or during heavy throttle usage, then the forced knock test may be failing. This is done by the ECM once the engine is up to temperature and the ECM goes into PE mode (WOT). Timing is added to force knock to occur. If it does occur everything is OK.

If after 2 attempts to force knock fail to produce knock (as seen by the knock detection system), code 43 is thrown and timing is reduced (will feel a loss of power after that).

The forced knock test can fail from too high an octane fuel, or improper base timing. Engine mods can also affect this test. Of course a bad knock sensor or module will also cause this to fail. Although you could probably hear the poor engine knocking away.

RBob.