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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15133
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a 2003 Yukon, 5.3L engine. Been having engine light

Customer Question

I have a 2003 Yukon, 5.3L engine. Been having engine light on for a few months; still trying to fix problem. Intake gasket replaced, not resolved. Just last week it started flashing as well. Took to another mechanic; they replaced fuel filter, fuel pressure relator; and one oxygen sensor. They said they drove it and it was fixed. I drove it - check engine light stilll on. I called and they said I need to replace my gas cap. I have not done that yet. As I drove it home anytime I go over 30 mph (whether in gear or in neutral) the engine light flashes. I go under 30 mph, and it goes off. It also randomly runs smooth, then a little rough. I am trying to figure out what is wrong I've paid almost $1000 to fix this and I don't have anything left to take to another mechanic.
JA: Diagnosing the correct check engine code is the key to getting a quick fix. Fortunately, the mechanics we work with have tons of experience dealing with this type of thing. Are you hoping to fix this yourself?
Customer: I am considering that. My husband has auto mechanic experience, and I am pretty handy but don't know if this is over my head.
JA: Is there anything else the Chevy Mechanic should be aware of about your Chevy?
Customer: Hmmm. It's been kind of a lemon. We bought it at 80,000 miles and have replaced tons of stuff; including transmission. This is our first enginie/fuel/spark problem though.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Chevy Mechanic about your situation and then connect you two.
Submitted: 6 months ago.
Category: Chevy
Expert:  Roy replied 6 months ago.
good evening my name is ***** ***** I will assist do you know what the codes are that set the check engine light??? that will help us narrow down the area of failure Roy
Customer: replied 6 months ago.
I can get it scanned again. I went to O-Reilly first and they said it was "a bunch of codes" I can take it in again tomorrow and get it read again.
Expert:  Roy replied 6 months ago.
yes, thats where we need to start Roy
Customer: replied 6 months ago.
Ok here are the codes
U1000 class 2 data link malfunction
PO135 02 sensor heater bank 1 sensor 1
P0200 injector circuit
P0300 random multiple. misfire
P0443 evaporative emission system. purge. control
P0446 evaporative emission. system. vent control. circuit
P1380 misfire detected
P0308 cylinder 8 misfire
Customer: replied 6 months ago.
I forgot to mention we drive on dusty muddy roads often.try to drive carefully. the car has appx 105000 miles on it. muddy roadsoften. i.
Customer: replied 6 months ago.
Sorry i am sending from cell phone and trying to type around a popup ad. i think all codes were typed correctly
Expert:  Roy replied 6 months ago.
ok, thanks, ***** ***** a bit to sort them out
Expert:  Roy replied 6 months ago.
ok, boy, the guy who looked at it for you missed the ball. the 135 is a bad heater in the O2 sensor. most likely needs to be replacing the drivers side upstream O2 sensor200 is a circuit issue with the injectors. need to check the harness and all the connectors to the injectors.300 is a random miss fire code. most likely failure is a bad fuel pump. the pressure is low and not up to specs.443,446 are evap codes. most likely cause is either a bad cannister purge valve and/or cannister vent solenoid. both are common failures.1380 is related to the 308 for miss fire on cylinder 8. these may be related to the 300 code.
Customer: replied 6 months ago.
OK, this is a little strange. My husband checked and it was the driver's side 02 sensor they replaced. We still are investigating the other items. So if the sensor was replaced, I wonder why it would still be showing a code for that? Also, at first glance he could not find anything with the injectors/harness, but that can be looked at closer. Not to the evap stuff yet. Do you have advice on the 02 sensor code issue?
Expert:  Roy replied 6 months ago.
it could be wiring going to the sensor. also, there are fuses for the heater circuit in the fuse box. check them with a voltmeter to be sure they are good. Roy

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