Check engine light code P0117, engine overheating?

PEDROV

MEMBER
2007 MAZDA 3
2.3L
4 CYL
2WD
AUTOMATIC
190,190 MILES

It all started with a leaking Water out flange...
-removed and noticed gasket and housing had failed. Replaced and filled with coolant. Leak fixed
-days later engine began to overheat after a short drive, off hunch I replaced Thermostat and filled with coolant. Engine was still overheating.
-days later I bought obdII scanner and read codes p0117. I reset codes and car ran like normal. Everything ran fine. I monitored the temperature, and it was going smoothly. Fans kicked at a good temperature. So, I went on a drive.
- During the 10–15-minute drive everything was still going good, I thought I had fixed the issue. Then on my way home the issue returned, temp shot up to 285F on my reader then car gauge slowly climbed up to High then began to drop to below Low point on gauge. The scanner still read hot temperature from 234,240,285F.
-I bought t stat at auto zone and water outlet flange on Amazon. Could this be an issue?

1 Reply

BORIS K

MECHANIC
799 POSTS

Hello,

P0117 is a generic OBD2 code. It indicates that your Mazda 3’s PCM has detected the signal coming from the engine coolant temperature (ECT) sensor has a voltage level below its normal operating range.

While P0117 is often caused by a bad sensor or wiring issue, you should treat it like the engine is overheating as the fault can also be caused by a physically overheating engine.

One reason for an overheating engine after cooling system repair is a possible air lock.

How to fill the cooling system

Refill the coolant into the coolant reserve tank up to the MAX mark on the tank.
Fully installed the cooling system cap.

If the engine coolant level in the coolant reserve tank is below the MIN mark during engine coolant air bleeding operation, stop the engine, and after the engine coolant temperature decreases, add engine coolant. Then, resume the engine coolant air bleeding operation.
Start the engine and idle it until the thermometer indicator is in the center when the engine is at below 1,500 rpm.
Bleed the air by following the procedures below. At this time, be careful of the coolant temperature to prevent overheating.
Note: If the accelerator pedal is depressed continuously for a specified time, the engine speed may decrease to the idle speed. This is due to the fuel cut, which prevents overheating, and it does not indicate a malfunction.

(1) Run the engine at 2,500 rpm for 2 - 3 min, 2 times.
(2) Run the engine at 3,000 rpm for 5 s, then idle.
(3) Repeat steps (1), (2) twice.
Stop the engine and inspect the coolant level after the coolant temperature decreases (water temperature gauge indicates 'C' or less).
Check the coolant level.
If it is low, refill the coolant into the coolant reserve tank up to the MAX mark on the tank.

A video:
https://youtu.be/iwjsWcg_qrw

Check the coolant temperature sensor, connector and wiring
See image 1 for wiring diagram

A good video on sensor location, covers fault P0118:
https://youtu.be/lnbR4q7jupQ

As you replaced the outlet coolant flange, the flange incorporates the sensor.
It could be a bad quality part if the sensor came with the housing

Cheers, Boris

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