5
When to Read Codes
Use the Code Scanner to read computer
trouble codes if...
• The “Check Engine” light comes ON
or,
• Vehicle engine is running poorly (for
vehicles without a “CHECK ENGINE”
LIGHT.
The Check Engine light
The “CHECK” engine dashboard light
tells you when to use the Code Scanner
tool.
The light may be colored amber or red,
labeled with a small engine picture,
called “CHECK ENGINE”, “PGM-FI”, or
“PGM-CARB” on some vehicles.
What the CHECK Engine Light
Does
when no problem is spotted
Normal operation:
• Light OFF – when the engine is
RUNNING.
This means the computer sees no
problem at the present time.
• Light ON –- when the ignition key is in
the ON position, but the engine is
OFF. (For example, before you start
the engine.) This is a normal test of all
dashboard message lights. (Depend-
ing upon vehicle, light will go out after
2 seconds or when engine is started.)
If the “CHECK” engine light does not
come on, you have a problem which
needs repair. Refer to your vehicle
service manual. Look in sections called
“Computerized Engine Controls”,
“Electronic Engine Controls”, “Tune-Up
Information” or similar.
What the CHECK Engine Light
Does
when a problem is spotted!
• Light ON and stays ON (when the
engine is RUNNING)
–The computer sees a problem that
does not go away. (A “hard” failure.)
–The light will stay on as long as the
problem is present.
–A trouble code is stored in computer
memory. (A “hard” code.)
–Use the Code Scanner at the
earliest convenient time to obtain the
code.
or…
• Light ON and then goes OFF (when
the engine is RUNNING)
–The computer saw a problem, but
the problem went away. (An
“intermittent” failure.)
–A trouble code is stored in computer
memory. (An “intermittent” code.)
–The light went out because the
problem went away, but the code
stays in memory.
–Use the Code Scanner at the
earliest convenient time to obtain the
code. Note that the computer will
automatically erase codes after
several restarts (typically 30 to 100)
if the problem does not return.
(Exception: some early Honda
systems do not have this automatic
code erase feature.)
A Poorly Running Engine
Some vehicles do not have a “CHECK”
engine light to let you know when trouble
codes are stored. If your engine is
Summary of Contents for Code Scanner CP9025
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