Checking Readiness Code Status

Readiness Code Status: Complete vs. Incomplete
Under current federal regulations, all readiness codes on a vehicle must read COMPL (Complete) before the OBD I/M test can be concluded. During these tests, readiness codes are used to show which emissions control systems have had their operational status tested. The Environmental Protection Agency (EPA) is proposing to let states conclude the testing process on '96-'00 vehicles with two or less readiness codes reading INCOMPL (incomplete). For '01 and later vehicles, the I/M testing process could still be concluded provided there's no more than one readiness code reading INCOMPL. Check your state's I/M program to see if this EPA proposal applies to your area. Readiness codes are also a great way to check if a repair has been effective or not. But keep in mind they don't indicate pass/fail status of the emission control system. If a fault is detected during monitoring, the readiness code will change to COMPL and a DTC will set to identify the fault. The combination of readiness codes and DTCs indicate the operational status of the emission control system.


Watching the MIL to Read Readiness Code Status
Readiness codes (also called diagnostic readiness codes or readiness/function codes) tell you if a specific emissions control system monitor has completed all testing needed to determine the operational status of the related system. This process of testing until the operational status is determined is refered to as "monitoring" the emissions control system.

You can check readiness code status by watching the MIL on the gauge assembly or using the PGM Tester. If you don't want to hassle with the PGM Tester, MIL watching is the way to go. Just turn the ignition switch to ON (II) (but don't start the engine), and keep your eyes on the MIL.
- If all readiness codes are complete, the MIL comes on for 20 seconds and then goes off.
- If one or more codes are incomplete, the MIL comes on for 20 seconds and then blinks five times.


No Readiness Codes? Check Back-up Fuse
On all OBD-II equipped vehicles, if all of the readiness codes read INCOMPL (incomplete) on the PGM Tester screen, check the ECM/PCM backup fuse before doing a lengthy test-dnve. If the ECM/PCM doesn't have battery back-up voltage, the readiness codes are reset every time the ignition switch is turned to LOCK (0).