2013 PACCAR MX-13 – P0115 Coolant temperature – Data erratic, intermittent, or incorrect at ignition on

Fault code information

2 trip MIL
3 drive cycle recovery
Readiness group – None
Freeze frame type – Cooling

Description of component(s)

Freeze frame type – Cooling
The coolant temperature is measured in the coolant return gallery at the right rear end of the cylinder block.
Effect on the system:
* Calculates the quantity of fuel to inject and the injection timing
* Displays the coolant temperature to the driver
* Displays warnings to the driver concerning high coolant temperature
* Limits the engine torque when the coolant temperature is too high
* Limits the maximum engine speed when the engine is cold
* Enables condition for severity of (OBD) diagnostic checks
* Fast idle speed control
* Cold start aid

Location of component(s)

Diagnostic condition

This diagnostic runs:
*  when the ignition has been keyed off continuously for at least 8 hours;
*  difference between the coolant and ambient temperature is less than 15°C [59°F];
* ambient temperature is more than -20°C [-4°F]

Set condition of fault code

The PCI ECU (D420) detects that the measured coolant temperature differs by more than 3°C [37°F] from the average of other temperature sensors on the engine for more than 5 seconds (after the ignition has been keyed off for at least 8 hours).

Reset condition of fault code
The 8-hour ignition off diagnostics consists of three separate steps:
* The vehicle ignition may NOT be switched on or engine started for 8-10 consecutive hours (ideal               situation would be overnight).
* Once the 8 to 10 consecutive hours have been reached, key on the ignition (NO engine start) and wait     for 10 seconds to allow the system to power up and the diagnostics to run.
* Start the engine and let it idle for 2 minutes.
* This DTC changes to inactive when the fault is no longer detected.

Electrical diagram(s)

Technical data

Possible causes

* Engine (block) heater used
* Coolant temperature sensor deviation

Additional information

For this diagnostic, the engine coolant temperature sensor (F566) reading is compared with average readings of other temperature sensors on/off the engine after the ignition has been keyed off for at least 8 hours.

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