Hi all, 1st post here. I have a 2003 H2 with around 110k. The issue I am having is when the vehicle gets warmed up, it will stall and will not restart. It will however restart after you let the vehicle cool down (30 mins or so). I had a similar issue last year, and after replacing a fuel pump, filter it ended up being a $20 water temp sensor. So this years symptom seems very similar to last years issue, but the sensor didnt fix it this time.

So far this time I have replaced the water temp sensor, ignition switch, put sea foam in tank and ran for a while, cleaned throttle body, MAF air sensor (last year replaced), had battery tested. I can speed up the shut off time by putting vehicle under load, like dive it.

It also is not throwing a codes. Anyone else have this issue and if so, what did you do to resolve.

Thanks in advance

 

it could be a crank or cam position sensor failing when hot but you would have to watch all your sensor data with a really good scan tool. then see if they are still outputting data when it fails to start.

 

Could be, but I believe those will throw a code. I am getting no codes, check engine light or anything..

 

no an intermittent crank or cam position sensor will usually not set a code. it would just show the symptoms you describe. that is is why it needs to be monitored when you have the no start issue when hot. i am not telling you to throw parts at it. be smart and verify if it's the issue before spending anything on parts.

 

You installed a "water temp sensor' 2x? You can't put a water sensor in an ICE.

 

Hi Sir

Out of curiosity did you ever figure this out?

 

That happened to me two weeks ago, It set a code and my 09 H2 stumbled while driving. I stopped for breakfast with my bud ...came out and popped the hood. Saw nothing closed the hood and fried right up and ran. Put the code reader on I had with me and cleared the code. Drove home ..next day put a new CSPS in and all is good. These are the codes I got......

Google:
​​​​​​​Can I drive with code P0335?
Other Notes About P0335

You shouldn't continue to drive your vehicle once it triggers this code. An issue with the CKP can cause your vehicle to stall—and that can be dangerous. Get your car diagnosed immediately if you run into this trouble code (or the related trouble codes P0336, P0337,

 

I have the issue going on and did fuel pumps and all the normal suspects, GM tech believes it maybe the Cam Actuator... mine is a 2008. Anyway to confirm before getting the work done?

 

I am having same issues but I cannot not get it to start and run to monitor anything. Mine just shut doshut way to work. I have only swapped fuel pump so far though. It turns over and fires but shuts down. I am interested in anything info on this post. No hijacking but have same issues

 

It's pretty common in all of the LS engines prior to the 6.2. (Which is the different camshaft position sensor in the front cover)

Usually it's the camshaft position sensor located at the very rear of your valley cover. Typically goes bad and will not throw a code. The crankshaft position sensor tends to be more reliable, but fails as well. (Located above the starter)

Very important that both are OEM ACDelco. Aftermarket camshaft position sensors are known to have intermittent reliability.

It's advisable to replace them separately.... Do the camshaft position sensor, and start the vehicle. If it fires immediately that confirms the problem. And simply due to age, especially if it doesn't start at this point, then do the crankshaft position sensor.

While the vehicle should start and seem to run fine, it will usually need what is called a CASE relearn. Most bidirectional scanners in the $150 range can perform this relearn. It will be referred to as a crank or Cam relearn in their literature. Or you can take it to just about any shop, or the dealer.... Or they will charge you between $150 and $170 to perform this relearn.

I hate just throwing parts at an issue without confirming.... The exception is this particular set of symptoms, usually caused by the camshaft position sensor... For the simple reason that when they go bad you typically do not get a code in the ECM. The only way to know for sure is to replace it.

And yes, easiest way to get to the camshaft sensor is to pull the intake. On the list of things to do "while you're in there"... Depending on your budget of course.... Might as well replace the oil pressure sending unit, the knock sensors, and the valley cover gasket. You'll probably find a couple of those bolts quite loose. Blue loctite on assembly. And again, AC Delco sensors unless you want to dive back into it again in 6 months or less.

In the end, if that doesn't do the trick for you, you've eliminated the most likely possibility.... And can start thinking about the ignition circuit all the way through to the ECM.

To give you an example of how difficult is to diagnose a defective one..... Sometime ago I replaced all sensors on a 2003 LQ4 6 liter, and it would never fire on the first crank. It would always fire immediately on the second crank though. Brand new sensor. Buddy that works at the local GM dealer said bring it over and we'll look at the live data while it's cranking. It showed time and time again the cam sensor was sending the necessary signal. We replaced it anyway knowing the history of these sensors. And it fired up immediately on the first crank. Most shops will not change anything that appears to be working okay on the computer. And they end up selling you an ECM and all sorts of other parts in a vane attempt to find the problem, before giving up. Keep in mind we're talking about a 16 to 20-year-old vehicle..... And most of the tech guys even at the dealer, aren't very familiar with these unless they've been working on GM's for 25 years or more.....