DTC P0128 - low coolant temp. After car had warmed up this morning I noticed the check engine light on. Looked under the hood and saw the coolant reservoir empty. Grabbed the large hose to the radiator, not sure the technical name, and tried to squeeze. Usually I can squeeze it and hear some bubbles in the line and it will push coolant back into the reservoir. Today it was hard as a rock, wouldn't budge. Could this be a faulty T-stat not letting coolant get back to the reservoir? Thanks, Carsten
you have no coolant touching the sensor, that's why it's reading low. The sensor needs to be surrounded by coolant, for an accurate reading. Take care of the obvious issue NOW, then troubleshoot again when everything normalizes. Chances are that your exhaust gas heat exchanger is leaking; assuming you haven't damaged the engine by running it like that. Hope this helps...... PS there should be NO air bubbles in the upper radiator hose when you squeeze it - that would indicate a leak somewhere that's allowing air into your cooling system making it less efficient.
Thanks, the heat exchanger has been bypassed, it had been leaking hence the bubbles. Is the pressure in the hose normal, as in not being able to squeeze fluid back into the reservoir? And where is that sensor? Thanks again
You can't squeeze the hose because there's no coolant in there, warming the rubber and softening it. Do you have a flow though coolant bottle setup or an old school reservoir? If old school reservoir, check under the radiator cap for coolant. LET ME BE CLEAR!! Your running your engine without any coolant in it, burning up your motor !!!
I feel like a bonehead, I went to add more coolant and that released the pressure, duh. I had been adding so much coolant before the bypass and hadn't gotten the trouble code that i was really surprised. Maybe it's just cause we're heading into winter and the ambient temps are lower...
Great; hopefully no damage has occurred.... Keep an eye on coolant levels for the new few weeks as more air will eventually works it's way out of the system. Good Luck.....
No, low engine coolant is not caused by the recent lower ambient temperature. You have a coolant leak somewhere that needs to be located and fixed. Who did the exhaust gas heat exchanger bypass?
