An OBDII scan tool, like the Actron CP9125, can be invaluable for diagnosing car problems. One common message displayed by these tools is “IM EGR System Mon Inc,” indicating an incomplete monitor status for the Exhaust Gas Recirculation (EGR) system. This message often appears alongside other incomplete monitors like the O2 sensor and catalytic converter (CAT). But what does it mean, and how can you resolve it?
Decoding “IM EGR System Mon Inc” and Other Incomplete Monitors
“Mon Inc” simply means “Monitor Incomplete.” The OBDII system constantly monitors various vehicle components, running specific tests to ensure they function correctly. When a monitor is incomplete, it signifies that the necessary driving conditions haven’t been met for the system to complete its self-diagnostic tests. This often happens after a battery disconnect or ECU reset, which clears the monitor status. It doesn’t necessarily indicate a problem, but rather that the system hasn’t had the chance to confirm everything is working as it should.
Specifically, “IM EGR System Mon Inc” relates to the EGR system, responsible for reducing harmful emissions. Similarly, incomplete O2 sensor and CAT monitors mean those systems also haven’t finished their tests.
Example of an Actron OBDII scan tool displaying various monitor statuses, including potentially incomplete monitors.
Why Are Monitors Incomplete and How to Complete Them
The most common cause of incomplete monitors is insufficient driving under specific conditions required to trigger the system tests. Each monitor has its own set of criteria, often involving specific speeds, engine loads, and temperatures. For example, the EGR monitor might require driving at highway speeds for a sustained period followed by deceleration without braking. The O2 sensor monitor might need several warm-up cycles and varying engine speeds.
To complete the EGR, O2 sensor, and CAT monitors, you typically need a combination of city and highway driving. This might include:
- Steady highway cruising: Maintaining a speed of 55-60 mph for at least 5 minutes allows the system to monitor emissions at higher speeds and loads.
- Deceleration: Coasting down from highway speeds to around 20 mph without braking or rapid acceleration allows the system to test various components under different engine load conditions.
- Varying speeds and driving conditions: A mix of city driving with stop-and-go traffic, acceleration, and deceleration helps ensure all test parameters are met.
Driving on highways and varying speeds are crucial for completing OBDII monitor tests.
Consult your vehicle’s repair manual or specific instructions for your Actron OBDII scanner (like the CP9125 manual referenced earlier) for detailed driving cycles to complete these monitors.
Implications of Incomplete Monitors for Emissions Testing
Incomplete monitors can prevent you from passing an emissions test. Since the system hasn’t completed its diagnostic tests, the testing facility can’t verify if your vehicle meets emissions standards. It’s crucial to complete all monitors before heading to the emissions testing station. If you’ve recently had work done on your car that might have triggered a reset, ensure you drive enough afterwards to allow the monitors to complete their cycles.
Troubleshooting Persistent Incomplete Monitors
If you’ve driven extensively under varying conditions and the monitors remain incomplete, a potential problem within the corresponding system might be preventing the tests from running. In this case, further diagnosis with a professional-grade scan tool might be necessary to pinpoint the issue. Faulty sensors, vacuum leaks, or wiring problems can all contribute to persistent incomplete monitors.
