Need Help Finding P0598 and P0102 Low Voltage Causes

[red_pig_ears]

P0598 Thermostat Low Voltage
P0102 MAF Low Voltage

I had these two codes pop up simultaneously and found a post here that had the same issue and mentioned a blown fuse but didn't say which one.

I found a blown fuse under hood and it's fuse #23, ECM 4. I replaced the fuse and the code went away for a few moles on my test drive but the next morning they came back on startup with cold engine. The fuse is blown again. The connectors and wires to the MAF and thermostat housing look fine.

Last september I replaced the thermostat housing but have never touched the MAF. The thermostat housing I bought was an off-brand to save a few bucks but I suspect it might have a short or something that's blowing the fuse.

How can I test the thermostat or MAF to see if they are both still good? Any other ideas what could be blowing this fuse?

 

[red_pig_ears]

The cause of the blown fuse was one of the sensors in the thermostat housing. The sensor itself is heated and it must have gone bad and thats what was causing the fuse to blow. Replaced sensors on the thermostat housing and all was good.

 

[baadharley]

Wow, just found this and wished I would have known this all before!! THANKS so much for the info/share!!!

My scenario, this is(now) the 4th therm housing/assy I have replaced!! The first factory one with the half plastic/alum is a MISTAKE and warps/leaks!! Anyway, car now has 159k miles on it and I've been replacing these with the Amazon equivalent and probably not the best idea, but they're cheap. Replacement #2 lasted for years/no issues and MIL went off after driving for a bit. #3 I replaced about a month ago and reset MIL codes P0597, P0598, and P0102. MIL codes again came up and fan seemed to be running when it shouldn't, though no high temp light, but yesterday, engine running really rough and almost wouldn't start.

So, after finding this thread, I went to local Autozone for a new Thermostat assy that is yeah, twice as Amazon, but Lifetime warranty for $115...I also replaced the MAF sensor for the P0102 code just in case.

Again, noticed this housing warped on the inlet side where gasket sits...Hmmmm...Then found YES the fuse #23 was blown!! After replaceing therm, fuse, and MAF sensor....all appears to be working as it should. Hopefully the MIL will go off after driving a bit. Heater works fine, so will update with results soon.

UPDATED: Glad to report, Autozone therm is working perfectly. No blown fuse and after driving a couple of trips, all MIL went off. No leaks and engine runs smooth. Only had to top-off coolant like 1/4".

 

[tabkey]

To someone who may be reading this in the future:
I have a 2014 Chevy Sonic 1.4L Turbo. I replaced the thermostat housing with a metal one, and after doing so, the check engine light came on. I had engine codes p0102 and p0598 thrown. After reading some forum posts, I checked the 10 amp fuse 23 under the hood, and it was blown. The electrical connection of the thermostat housing read 15.8 Ohms, so it was in spec. My guess was that I had gotten coolant in the connector and it shorted the circuit, thereby blowing the fuse.

If you have also recently replaced the thermostat housing, I would recommend using QD Electrical Cleaner on all of the connectors that were disconnected while conducting the replacement, then blast them out with compressed air, and let them sit to dry. After doing this, and replacing the blown fuse, the system is working properly.

 

[Dingleberry69]

If you have also recently replaced the thermostat housing, I would recommend using QD Electrical Cleaner on all of the connectors that were disconnected while conducting the replacement, then blast them out with compressed air, and let them sit to dry. After doing this, and replacing the blown fuse, the system is working properly.

yup great suggestion. Another thing I like to do is put a small dab of dielectric grease on the connectors as well. Helps prevent corrosion and helps prevent water ingress to maintain a good positive connection.