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That pesky check engine light, the "Malfunction Indicator Lamp" or "MIL" for short, is on because your vehicle's computer self-diagnosed a fault that could cause your vehicle's emissions to increase. It doesn't necessarily mean your vehicle is |
With the price of gasoline, you don’t want to ignore
this kind of problem for
long. When fuel economy is
down, you may find any
number of codes: • P0172 and/or P0175 are
rich codes and indicate a
general rich air/fuel
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 The OBD II Onboard
Diagnostic system that is
used on all 1996 and newer
passenger cars and light trucks
(as well as a few 1994 and 1995 models) will set a fault
code and turn on the MIL
lamp if it detects ANY problem
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 An engine that hesitates,
stumbles or misfires when
accelerating, or when it is under load is an engine that is
either sucking too much air,
not getting enough fuel, or
misfiring. If the Check Engine
Light comes on, you may find
any of the following codes: |
Chances are the Check
Engine Light is not on, but you
may find any of the following
codes: P0230 to P0233; Fuel Pump codes; P0600 to P0606;
PCM related codes; P0335 to P0339
Crank Sensor codes; P0190 to P0194
Fuel Pressure Sensor codes |
Stalls typically occur when the
engine is idling or slowing. If the Check Engine Light comes
on, you may find any of the
following codes: P0505 to P0509 idle control
circuit codes; P0335, P0336, P0337,
P0338, P0339 crankshaft
position sensor codes; P0171, P0174 lean fuel
condition codes; P0400 to P0409 EGR
related code.
The engine may be stalling
because it isn’t getting enough |
Allow the engine to cool
down for several hours before
you attempt any further
diagnosis. A hot engine can be
very dangerous because of
steam pressure inside the
radiator and coolant reservoir.
Do NOT attempt to add
coolant until the engine has |
Oxygen Sensors (O2)
Purpose: Measure the
amount of oxygen left in the
exhaust stream to provide
feedback to the computer
about whether the air/fuel
mixture is rich or lean. Symptoms: Poor fuel
economy, Rich fuel mixture,
Check Engine Light, failed
emissions test.
Tech Tip: Test for O2 sensors |
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Check Engine Light
after-market modifications
