Question about 2003 GMC Yukon XL

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Major freon leak, knock sensor codes present, reduced engine power more frequently occuring

Dye was ran through my system and no leaks found in easily visual areas. Its a major leak. When we charged it, you could smell a distinct smell and it was completely leaked out within 24 hrs. Also the computer is saying I need to replace the knock sensors and now the reduced engine power is coming on more frequently. Used to every few months and now 1 outta 3 times driving it happens. Seems to burn more gas as well. Needless to say, Ive parked it until the problems can be resolved. I have almost 260,000 miles on it and have been the only owner.

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I do not know what was done so i would check the oil for a milky color, if yes it has a bad head or head gasket, if no then pressure test the system and confirm it is leaking out then check the entire radiator and all the lines and hoses make sure the hose connections are not leaking at the radiator and drain, the overflow bottle could be cracked or leaking where the drain hose fitting is. One would think if it is leaking that bad it would be visible some where. check the radiator core for pinholes. if ithas tailoring check the coolers and lines for leaks and the cooler for pinholes.

Posted on May 04, 2017


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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
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Posted on Jan 02, 2017


SOURCE: 1998 Yukon high idle sound with bad gas mileage.

What you have is the torque converter clutch,cycling on and off.
When it is off.your rpm will go up and your milage will go down
First-check to see if your brake switch, on the back of the brake peddle, is loose or misadjusted. When you apply the brakes,the first thing to happen, is that you unlock the converter,so your trans is not connected directly to the motor,or you would stall. Then below 42 MPH,your trans is working off the converter, as a pressure multiplier ,based on rpm
Second- switch okey. You remove trans pan and change TCC Solenoid.

Let me know if if you need more guidance

Posted on May 08, 2010

Testimonial: "Thank you for the quick response. Figured it to be something with the trans. Gives me a good place to start and a good reason to clean out the other stall in my garage to work on it. Thanks again!!"

  • 477 Answers

SOURCE: about 3 weeks ago i was getting a code for the MAF

I'm going to go out on a limb and sugest that you look for melted wires in the engine compartment. That would explain the burning plastic smell. And a bare wire grounding on your engine could cause about 100 diferent problems.

Posted on Sep 20, 2010

  • 4399 Answers

SOURCE: I just bought a 2005

Thanks for choosing FixYa and welcome to the site. These big engines burn oil a lot, but not that much. If you haven't already, you need to get under the engine and check the back wall of the motor for oil leaks. Since there is no black smoke, your fine on the back end. Have you checked the back wall from underneathe? Also, is your check engine light on? Thanks.

Posted on Aug 16, 2011

  • 404 Answers

SOURCE: Had a code come up

Have you erased the error code in the CPU of your car? also sometime it can be the the control valve in the injector. I would get the car diagnosticsdone properly and than see how it goes.

Posted on Sep 18, 2011

  • 96 Answers

SOURCE: truck was running rough, threw a code 44. new o2 sensor, cleaned throttle body, new plugs and wires. checked fuel filter. found and repaired a major vacumn leak. it still ran rough and now threw a new

Glad you got it fixed. Chasing a problem can be very frustrating.

Posted on Sep 17, 2012

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2 Answers

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Major freon leak, knock sensor codes, reduced engine power

I would say your a/c evaporator may be the culprit for your leak. What code did it give you for the knock sensor replacement? I would give it a tune up if it has been awhile.

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Was it recharged last year because it was low? If so, a leak is probably present. An ultraviolet dye should have been installed when it was recharged. A black light can be used to see if any leaks are present if dye was installed. Either way, the freon pressures need to be checked as a starting point. If there isn't enough freon in the system, it will not come on.

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Would first start by having the freon pressures checked to ensure the proper amount of freon was in the system, if any at all. If system is low or empty, a leak is present. If system is low, ultra-violet dye would need to be injected into the system along with freon and run the system, checking with a black light to find the leak.

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Hi there:
What can happen is the vehicles Freon will leak out and reduce the total pressure in the system. Then the low-pressure cut out switch will disengage the compressor when the low side is detected below 25 psi.

This safety feature is to protect the compressor itself. I have seen mechanics bypass the low cut out switch for testing. This should never be done and is not recommended.

The visual presence of oil around a fitting or pressurized line is a strong indication of a refrigerant leak. So my first step in air-conditioning leak diagnosis is to perform a very careful visual inspection of the entire system.

Although this is always my first step for diagnosing Freon leaks it is not always effective in finding the exact problem. In fact, this visual inspection will only uncover large to extremely large leaks. A more common air-conditioning problem would be small leaks that allow Freon to escape over long periods of time. So to follow will be some methods to detect these small leaks.
- The Robinair leak detector is a hand held battery operated electronic leak sniffer. The test probe on the end of the leak detector is moved about 1 inch per second in the areas of suspected leaks. The Robin air leak detector has an alarm that will go off when it detects the presence of a Freon leak. Note on some other models they may have flashing lights or a buzzer. Also some leak detectors are specialized to detect only certain freons (example: 134a) but they all are designed to alert you when they sniff the refrigerant.
- To find refrigerant leaks using the fluorescent tracer system, you first have to install the fluorescent dye into the cars air-conditioning system. Always follow the instructions and do not install too much dye! Too much can reduce the cooling efficiency of the system. Different refrigerant dye leak detectors will accomplish this in different ways. The system we use at work has a device that looks like a caulking gun, and a hose that connects to the low side fitting. Then you actually push the dye into the low side with the engine running and the compressor engaged. Next you run the air-conditioning system for several minutes to distribute the dye evenly. Then you put on your yellow glasses and examine the system with a fluorescent light.
The fluorescent dye shows up easily wearing the yellow glasses.

A very popular selling item is Refrigerant with leak sealer. This item will only seal very small leaks. I have used the stuff pictured to the right "super seal pro" and it does work in some situations.

The Freon leak sealer works best when you have low side system leaks. And if you happen to have a small leak from an O-ring on the low side this stuff works well. If you have a leak on the high-pressure side chances are this sealer will not work for you.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day

Feb 15, 2012 | Cars & Trucks

2 Answers

Freon was low, the clutch would not stay in very long while trying to add the freon, I continued to put the freon in at a slow pace,after about 18 oz. the clutch did kick in and stayed in through out the...

Sounds like the freon was pretty low.The pressure readings are pretty low indicating possibly a weak compressor or freon is still low. Does this have rear ac as well?l You probably should have evacutated the system and put it into a vacuum. A very useful tool would be to inject a uv dye oil charge into the system and let it run with the ac still cycling which can still be done prior to evacuation.If there any leaks present the dye will seep out the leak and be easily detectable with a uv light.

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There's a leak in your ac system. Have a shop trace the leak. They would pump in a dye to locate the leak. It usually leaks in the compression seal

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Normally due to low freon. Also, notice if the a/c compressor clutch engages, as it will not if the freon is low.

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It is caused due to leaking from thermostat housing into crankshaft position sensor harness multi-plug

Check and clean the crankshaft position sensor harness multi-plug contacts. Rectify the engine coolant leak from the thermostat housing if found. Take a note of the engine coolant level and monitor it for changes, showing a leak is indeed occurring.

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1 Answer

I took my van to get checked for leaks but one of my hoeses was torn they replaced it and put new freon but the freon didnt last that long what could be the problem

Your system will need to be dye tested. If the hose that was replaced was properly installed and not leaking, next place I'd look is near the front of the compressor. Front seals on these units fail frequently. Dye test is best way to find leak.

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