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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29428
Experience:  GM Grand Master Technician 2007. 14 years experience.
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My 03 Yukon Denali XL some flashes the check Eng.

Resolved Question:

my 03 Yukon Denali XL some flashes the check Eng. light then go away i only seen this happen twice in a year
Submitted: 6 years ago.
Category: GM
Expert:  GM Tech (Cam) replied 6 years ago.

Greetings and Welcome to Just answer.

Does this happen when accelerating hard ot just random?

Customer: replied 6 years ago.

NOT SURE HAVENT PAYED ATENTION WHEN IT HAPPENS . I ONLY REMEMBER ABOUT THIS PROBLEM WHEN I SEE IT FLASHING . ALSO SOME TIME AT A STOP TRUCK FEELS LIKE WANTS TO STALL.

Expert:  GM Tech (Cam) replied 6 years ago.

Ok, does the check engine light remain in solid all the time?

 

Customer: replied 6 years ago.
ON IT FLASHS RAPPETLY
Expert:  GM Tech (Cam) replied 6 years ago.

OK, when was the last time you changed the fuel filter, change the plugs, clean the throttle plates and the Mass Air Flow Sensor at the air filter?

 

Customer: replied 6 years ago.

recently changed fuel pump ,fuel filter (8 months) truck has a volant cold air intake, granatelli mass air sensor , bbk throttle body , ( oversize throttle body). also i just remembered some times when accelerating hard the light comes on solid only happen about three times i cant recall the code some thing like air mixture or fuel mixture i cant recall

Expert:  GM Tech (Cam) replied 6 years ago.

IS the air filter one that you put oil on?

 

Customer: replied 6 years ago.
yes and my plug are denso iridium
Expert:  GM Tech (Cam) replied 6 years ago.
Ok, clean the Mass Air Flow Sensor with carb cleaner. The oil coats the sensor and can make the sensor read wrong.
Customer: replied 6 years ago.
how about this denso plug i read on other post bosh plug where not good for gm ?
Customer: replied 6 years ago.
i heard that flashing Eng. light is bad they say stop driving car when it comes on
Expert:  GM Tech (Cam) replied 6 years ago.

Sorry, it was supper time.

Teh Bosch is not a good plug.. You are better to use a NGK or AC Delco.

Flashing check engine light is causing damage to the converters so if it is flashing, then you should not drive it.

 

Customer: replied 6 years ago.
so denso plug are OK ? the flashing Eng. light I've only seen come on twice or maybe three times doesn't stay on it goes away what could that be?
Expert:  GM Tech (Cam) replied 6 years ago.

There is a misfire that is happening to cause the flashing light. It could be from the oil on the sensor, it could be something in the injector, intake leaking or anything like that. If all the things I suggest don't work, then you need to use the scan tool to see what cylinder is leaking.

 

Customer: replied 6 years ago.

am cleaning out the air filter cleaning mass air with carb cleaner. how do i check for something in the injector, intake leaks ?

Expert:  GM Tech (Cam) replied 6 years ago.
Spray carb cleaner around the intake with it running to see if there is a difference in the way the engine runs. Injector leaks need a flow test to check them.
Customer: replied 6 years ago.
Injector leaks need a flow test to check them. only shop can do a flow test ? or is it something i can do ? if so how do i test and what am i looking for
Expert:  GM Tech (Cam) replied 6 years ago.

the tools required are in a shop and not worth spending the money for one test.

 

GM Tech (Cam) and 2 other GM Specialists are ready to help you
Customer: replied 6 years ago.
today when turn on suv it was shacky like wanted to shut off the check eng. light came on drove the suv from work to my home put a scanner to it . code po200, and po300.came out . havent use suv for about a week i dont if that has something to do with it.