94, 740 I, Check Engine Light

My 740 I began to run roughly and the check engine light on.
I used the Bentley Manual and got the code that said "too Rich Mixture".
Checked the air filter, it flunked the "see through it" test.
So I changed it.
The car runs good again but the Check Engine Light remains on.
Anyone know how to clear that light?
Any info appreciated....

The check engine light staying on can mean 2 things. One is that you still have another problem. For some codes the light will go off once the problem goes away. Some it stays on until reset. If you do not have any other problem codes (you read 1444 when checking the code). Then you will need a reset tool. You can find two companies that sell the reset tools in your Bentely manual. I personally use the Peake reader/reset tool. It will also reset the oil change indicator and read the codes from the interface under the hood (some that are not obdI) which is a plus. But is more expensive than the Peake reset tool.