Po 174/175

Got a check engine light on this morning on my 2004 Chevy Suburban 5.3. Looks like its a PO174/175 codes. There is no hesitation or miss fire. Truck runs great and still gets great fuel mileage. Added a quart of oil as it was about a quart low and thats about it so far. I'm thinking either MAF sensor or O2 sensors right now. Any other ideas?

Got a check engine light on this morning on my 2004 Chevy Suburban 5.3. Looks like its a PO174/175 codes. There is no hesitation or miss fire. Truck runs great and still gets great fuel mileage. Added a quart of oil as it was about a quart low and thats about it so far. I'm thinking either MAF sensor or O2 sensors right now. Any other ideas?

recheck those codes 174 is lean...175 is rich ...can't be both..

Figures...I had it done at Autozone....I guess I'll get it checked out again tomorrow. Thanks man.

recheck those codes 174 is lean...175 is rich ...can't be both..

Ok, so I went back to Autozone and found out that its a PO171 and
PO174...please tell me that this isn't a gasket issue cause I had to deal with that with my 5.7 Tahoe...it was a pain in the a$%!!! Looks like the check engine light turned off as well on way back home....maybe a false alarm?

Also, I noticed that it takes about 5 minutes for the heat to start working, which is a little unusual as it never took that long before. The heat works fine on the freeway, but when I do stop and go in the city the heat gets cooler and I notice the needle on the thermostat get a little hotter then go back again, then the heat starts working better. Do you think I have a bad thermostat as well? Thanks for any info.

So now that I got the oil topped off and added about a quart of dexcool everything is good to go. No light, heat works fine...will keep everyone updated.

Went to work this morning and the check engine light never came back on. The heat also works just fine and no issues with thermostat...not sure why only adding that much of coolant solved all the problems? All I did was fill up to the cold fill full line...probably wasn't even a quart worth. Anyway looking forward to spring and/or warmer weather so I can do a little tune up.

Went to work this morning and the check engine light never came back on. The heat also works just fine and no issues with thermostat...not sure why only adding that much of coolant solved all the problems? All I did was fill up to the cold fill full line...probably wasn't even a quart worth. Anyway looking forward to spring and/or warmer weather so I can do a little tune up.

when filling coolant with cap off cold engine start engine then continue to fill and rev engine a few times...do this until operating temp..this is how to remove air...then after a few days repeat this to ensure you have no leaks...these small leaks can damage you engine..

check for leaks around the water pump, these gaskets are a big problem ..check the bolts holding the water pump for security..

when filling coolant with cap off cold engine start engine then continue to fill and rev engine a few times...do this until operating temp..this is how to remove air...then after a few days repeat this to ensure you have no leaks...these small leaks can damage you engine..

check for leaks around the water pump, these gaskets are a big problem ..check the bolts holding the water pump for security..

Alright, I'll give it a go when the weather breaks. I'll let you know if anything changes.

Still no issues at this time.

Good!
The Plastic, rubber, seals, and gasket seems togo bad in time on the EGR, PCV, and air intake systems.
check www.automotiveforums.com/vbulletin/showthread.php?t=974347 (http://www.automotiveforums.com/vbulletin/showthread.php?t=974347)

Still no issues at this time.

sounds good,,but if you did have to add a quart it went somewhere ..should check these levels every week..

sounds good,,but if you did have to add a quart it went somewhere ..should check these levels every week..

Forgot I had this thread...heat still works fine as i make sure to keep the coolant level...still can't find the coolant leak though...nothing around the water pump and system is air tight...I'm thinking that I probably have a lower intake gasket that needs replaced. Is it a pain to replace the gaskets in the 5.3's like the 5.7's were?

Forgot I had this thread...heat still works fine as i make sure to keep the coolant level...still can't find the coolant leak though...nothing around the water pump and system is air tight...I'm thinking that I probably have a lower intake gasket that needs replaced. Is it a pain to replace the gaskets in the 5.3's like the 5.7's were?

if the coolant is being sent to the intake to be burned the O2 sensors would be all destroyed by now...

this leak could be the heater core hoses..leaks drip on the manifold when engine is running ..this has occured to some..

loosing fluid can't find where !

get a white cloth and rap around those plastic couplings at the heater core piping..

Great so I may have new o2 sensors to get...haha...I'll check out the heater core lines...thanks for the help.

Great so I may have new o2 sensors to get...haha...I'll check out the heater core lines...thanks for the help.

no! because the computer would have thrown a code if you DID have coolant being burned ! since no codes this must be external to the engine intake ..

no! because the computer would have thrown a code if you DID have coolant being burned ! since no codes this must be external to the engine intake ..

Yeah, sometimes I get a 171/174 code, but then it goes away....happens everyone once in a blue moon...I'm pretty sure it may be related to the coolant loss as I got the same codes when I was burnin coolant in my tahoe...I'll check the heater lines tonight...see if I can find any evidence of the coolant leak.

Just checked as well I could for leaks...not a drop anywhere...no staining...no nothing...didn't smell anything either...My gut says I need to change the damn intake gaskets...did a little research on the web and it seems to be a common problem...just don't understand why chevy can't get something as simple as a good sealing gasket right.

I just had this code (PO174) on my 2006 Silverado 4.3L. The truck would run rough when started and gave me a couple of hard starts. Once driving, it ran fine. I asked my son in-law mechanic if he would run it on his analyzer. We eliminated the fuel pump and filter, as we had good pressure (62 PSI). The Mass air flow sensor was good. He then took off the Emissions Purge Valve and put a cap on it. This was the culprit. I went to Autozone to get the replacement purge valve and put it on. As soon as I started the truck, it was back to a smooth idle and the Check Engine Light went off. Problem solved. The part cost $36 and is located on top of the engine behind the throttle body, closer to the firewall. It has a vacuum line and electric plug on it. it was easy to replace. Good Luck.:smile::smile:

you should of had some EVAP DTC codes..

I am getting the same codes, but it only occurs when the outside temp is below 40°F (which is most of the time in NE Ohio). As soon as the temp warms the codes go away.

The truck runs great, 5.3 with 245,000 on it.

Any ideas?

check the ECT for proper temp output signal. connector to it can get damaged pins corroded or just the sensor too old .. replace the O2 sensors upstream every 125K miles on these engines.