Hello,

My mother has a GM Hummer H3 (2006, 3.5l) and has a few codes
1.Manifold absolute pressure sensor
2.Coolant temperature sensor
3.Cylinder misfire #2

So I replaced the MAP sensor (OEM), Coolant temp sensor (AC Delco with 15mm crowfoot), and all 5 coil packs and all 5 sparkplugs too (NGK plugs)

And the misfire went away, but the MAP and the CTS code came back? (I know the sensors is good I replaced them with brand new?)

What I did notice is that the temp gauge only reads 1/4 of normal, and the fans turns on too early (not even getting near half way mark on the temp gauge).

And I just checked the resevoir and its low on coolant? What could it be?
Unfortunately my mother is going thru remission (unemployed because of her cancer) and cannot afford a shop, so she asked me to help.

Any help is greatly appreciated, and thank you in advance from me,
Fred

 

fans? "turn on?.fan is belt driven,not electric.
coolant low, add to proper line.

plugs, use only gm type.
temp reads low. could be sender. could be thermostat which is the complete temp control,the boss.
may need toproperly clean map sensor.ive not done it but its covered here hundreds of times.

misfire 2, swap coil pack to test?, injector?

mileage?

 

Welcome to the Forum, Fred.
Sorry to hear about your Mother. Where are you located? Maybe one of us local to you can give you a hand. For now, also check the connectors for the MAF and Temperature sensor, add coolant to the proper level and check for leaks. Disconnect your terminals and if original, replace them. You will not believe the effect that they will have with your truck throwing codes. Search through this forum for what you mentioned before and you will find numerous threads addressing those issues. Good luck. Jacques

 

Ok. Checked the OBD2 with my scanner and only (2) codes showed up
P0128
P0128 pending

Went to autozone and grabbed a Tstat and Tstat housing for $49.99 and couple gallons of coolant, and swapped out the part. Done.

Erased the CEL and bled' the coolant using a gravity funnel, and pinched the reservoir tube. Ran the car for about 10 min, and then another 5min with the heater full hot on low power (to cycle coolant in the heater core). And now the temp level is in the middle.

Going to go run errands with moms so we can add some mileage and I'm hoping (fingers crossed) that the CEL will go away.

I did notice that the original thermostat was missing the bar in hole. And the aftermarket one had it still in tact.

Thanks (I'll keep y'all posted)
Fred

 

WTF. Cylinder 2 misfire again?
P0302

 

u can swap stuff from 2 to4? see if it moves.
plugs, the i5 is fussy about plugs.
remember the 06 had head trouble??

 

Just say no to ngk! Acdelco yes or oem sparks.

 

I5s are very picky on plugs. OEM plugs only.

Try swapping coil packs and see if the misfire changes cylinders.

 

Use ONLY AC Delco plugs, through out the NGK crap you bought.

 

Okay. I'll buy some today. Does anyone know the correct part #?