p0118, CEL, coolant temperature sensor
 

Hello. I have a 09 Mini Cooper S Convertible and just did a thermostat housing replacement last weekend.

I replaced it with OEM thermostat housing with new sensors included.
After the thermostat housing replacement, I got a few code that popped up:

P0117, P0117P (GONE NOW)
P0118, P0118P with CEL light.

When I try to see the engine temperature through hidden option 7, it's not reading the temperature and showing CTMP-MOM ttt o C.

I refilled with coolant and bled it several times.

I usually have the engine temperature visible almost all the time to see if it's overheating, but now I can't see and making me nervous.

Yesterday, all of a sudden, the car had red colored engine overheating light on my dash. I pulled it over to the side, the a/c air was blowing warm. Turned off the engine, scanned, only p0118 code. After 1 min of shutting it off, it was back to normal.

I'm guessing it's my coolant temperature sensor that is bad? the brown colored clip with a U green clamp? Any advice would be great.

Thank u in advance.

-seb

According to OBD codes:

Causes

A code P0118 may mean that one or more of the following has happened:

A bad connection at the sensor
An open in the ground circuit between the ECT sensor and the PCM
A short in the voltage feed between the sensor and the PCM A bad PCM (less likely)
A bad temperature sensor (shorted internally)

Possible Solutions

First, if you have access to a scan tool, check the reading of the coolant sensor. Does it read a logical number? If so, the problem is likely intermittent. Perform a "wiggle" test by wiggling the connector and harness to the sensor while watching the reading on the scan tool. Watch for any drop-outs. Drop-outs would indicate a bad connection. If the scan tool reads an illogical temperature, check the resistance of the temperature sensor. If it is out of specs, replace it. If it is in specifications, unplug the sensor and, using a fused jumper wire, jumper the two terminals of the connector together. The temperature reading should now be maxed out to above 250 degrees F. If not, there is likely a problem with the ground circuit or voltage supply. Check for 5 volts reference voltage at the connector. Also check for ground presence at the connector. If you do not have 5V ref. and/or ground continuity, check for these back at the PCM connector. If you have these at the PCM connector, then repair open or short between the PCM and the sensor. If you do not, remove the offending wire from the PCM and then check for proper voltage at the PCM pin. If it's present now, repair short on the circuit. If it isn't present after removing the wire and checking the pin, replace PCM

NOTE: Usually, P0118 is indicative of a bad temperature sensor, but doesn't rule out these other possibilities.

See if any of this helps you diagnose the issue.

Wiring connectors
 

Also, make sure all the connectors are on the correct sensors. For some reason Mini has 3 leads coming off the same point on the harness that are all the same connector type. The temp sensor gets the white and yellow connector. The brown and black goes to the air hose next to the turbo inlet. The yellow goes next to the temp sensor

Thanks