seawolf18

iTrader: (18)

When coming home from work the other night my SES light came on. I figured it would be O2 sensor switching again. I took it to my local parts store with a scan tool. The code that came out was P0128 Coolant Thermostat Malfunction. What the hell does this mean? I cleared the code, and it has not returned. Any suggestions on what to check? Thanks.

2001NBMZ28

Could be the thermostat, ECT or IAT sensor. Visit gearchatter.com and look up the description/diagnosis for your year. Is the temp gauge acting normal?

seawolf18

iTrader: (18)

yeah, it sits where it always does, just under 210, and the coolant is full.

Smokin00WS6

iTrader: (4)

That sounds like a stat problem. I wouldnt screw with that. Just make this into a fun 160 deg stat project and call it a day.