The Check engine light and stop engine lights are for engine protection.
They come on to notify the operator of a current or potential problem. Many times a coach can be safely operated to the nearest
maintenance facility with a Check Engine light on. By obtaining the code, you can relay this information to maintenance and
they can determine if it is safe to operate the coach.
Types of Codes
There are two types of codes, active and inactive.
1. Active code; indicates a current problem. If a code is active the check engine light will be illuminated.
2. An Inactive code indicates a problem that occurred, but is not presently active. If the check engine light came
on, and then went back off, then the engine has logged an inactive code.
Obtaining Engine Codes
Use these steps to obtain inactive engine codes.
1. Turn the bus Master Switch on. Do not start the engine.
2. Momentarily depress the buses ‘engine override’ switch and monitor the check engine light
3. The check engine light should blink
4. Count the blinks, noting that there will be a few short blinks, then a pause, and some more short blinks. The first
set of blinks is the first number in the code, pause, the second set of blinks is the second number of the code. (eg. 2 blinks,
pause, 5 blinks = code 25)
5. After the first code, there will be a longer pause, then the check engine light will blink out the next engine code
if there is one. (eg. 2 blinks, pause, 5 blinks, longer pause, 4 blinks, pause, 3 blinks = code 25 and code 43)
Use these steps to obtain active engine codes.
1. Once the check engine light has stopped flashing, the stop engine light will flash all active codes. Note; the check
engine light is orange, the stop engine light is red.
2. Count the flashes of the Red Stop Engine light and it will tell you all active codes.
3. Count the codes two or three different times to be on the safeside and make sure you come up with the same code at least
three times in a row.
4. Once you have obtained all active and inactive codes, call maintenance to find out if the codes are critical, or if
the coach can be safely operated.
NOTE: any active code will become inactive once the bus is shut off and restarted. If the check engine light comes back
on after the bus has been shut off and restarted then the problem has occurred again.
Some Common Codes
This is a list of some of the more common codes.
25 = no codes
16 = coolant level sensor input voltage high
43 = coolant level low
44 = oil or coolant temperature high
45 = oil pressure low
46 = ECM battery voltage low
22= Throttle position sensor input voltage low
53 = ECM memory fault
71 = injector response time short