Error Code P063F is defined as Auto Configuration Engine Coolant Temperature Input Not Present. This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made since 1996 up to present. This may include vehicles from Hyundai, Kia, Mazda, Nissan, Toyota, etc. Specifications on the definition, troubleshooting, and repairs vary from make, model, and powertrain configuration.

When Error Code P063F appears, this means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) is unable to detect the auto-configuration engine coolant temperature input signal of the vehicle.

Modern vehicles conduct self-test as soon as the ignition cylinder is turned into ON position and various onboard controllers are energized (including the PCM). The PCM depends on the input signals from engine sensors to configure the engine startup strategy and perform these self-tests. One of the key input signal required for PCM’s auto-configuration is the Throttle Position.

The ECT (engine coolant temperature sensor) should provide the PCM (and other controllers) with an engine coolant temperature input signal for automatic configuration purposes. The ECT is a brass, steel, or plastic sensor that comes with a thermal resistor (suspended in resin) inside the tip. This sensor is usually threaded into the engine coolant passage, with its tip inserted into the passage. As the engine coolant flows, the tip of the sensor detects and affects the thermal resistor inside. When the engine coolant warms up, the ECT sensor resistance decreases, and circuit voltage increases. As the engine coolant temperature decreases, the ECT sensor resistance decreases, along with the circuit voltage.

When the ignition switched is turned ON to energize the PCM, but the PCM is unable to detect an ECT sensor input circuit, then Error Code P063F will be stored and activate the Check Engine light. Autoconfiguration system may also be deactivated, resulting in serious drivability issues.

Common Symptoms

This code causes drivability issues, such as:

  • Engine stalling at idle (especially at startup)
  • Delayed engine start

Other TPS related codes may be present as well.

Possible Causes

  • Defective TPS
  • Corrosion in TPS connector
  • Open or shorted circuit between TPS and PCM
  • Damaged or programming error in PCM

How to Check

If there are other TPS-related codes present, they must be diagnosed and repaired first before attempting to fix Error Code P063F.

For a more accurate diagnosis, you need a diagnostic scanner, DVOM (digital volt/ohmmeter), infrared thermometer, and a dependable vehicle information source.

Before starting your diagnosis, make sure to consult with your vehicle information for the applicable (TSB) technical service bulletins. If you see one that matches the vehicle symptoms and codes with what you’re experiencing, then it may speed up your diagnosis.

Start your diagnosis by connecting the scanner to the vehicle diagnostic port, retrieve all stored codes and their pertinent freeze frame data. Then, clear the codes and then take the vehicle for a test drive until one of the two scenarios occur:

  1. The code does NOT reset, and PCM enters readiness mode
  2. The code resets

If the code does NOT come back, then you’re dealing with an intermittent condition, which means the problem may have to worsen before you can diagnose it more accurately.

If the code comes back on the other hand, then continue with the diagnosis.

First Step

Check all the related connectors and wirings. Check the PCM power supply fuses and relays. Repair as necessary.

Second Step

Check the diagnostic flow chart, connector face views, wiring diagrams, connector pin-out charts, component testing specifications and procedures for your vehicle from the vehicle information source.

As soon as you have the right information, test the ECT voltage, ground, and signal circuits using the DVOM.

Third Step

Start the simple test at TPS connector, test for voltage and ground signals. If there’s no voltage, then use the DVOM to trace the circuit back to the right terminal of the PCM connector. If there is still no voltage on this pin, then you can suspect a defective PCM.

If there is a voltage at the PCM connector pin, however, then there’s an open circuit condition. You can proceed on repairing the open circuit between the PCM and ECT.

If there’s no ground, then trace the circuit back to the central ground location, make the necessary repair.

If there are ground and voltage at the ECT connector, then proceed to the next step.

Fourth Step

Know the actual temperature of the engine coolant using the infrared thermometer. The scanner data stream will show the temperature (or degree of voltage) being input to the PCM (if there’s any). Compare the voltage to the temperature information (found in your vehicle information source) to find out if the ECT sensor is working properly.

If the ECT and all system circuits are working fine, then you can suspect a defective or programming error in the PCM.

How to Fix

Depending on your diagnosis, common repairs for this code include:

  • Repair or replacement of damaged wires or connectors
  • Repair or replacement of open circuit between PCM and ECT
  • Replacement of ECT sensor
  • Replacement or reprogramming of PCM

Many vehicles use multiple ECT sensors; with one may be for the instrument panel gauge and the other for the PCM. Thus, make sure you refer with your vehicle information to make sure you’re testing the right ECT sensor.

Auto configuration for this code must be taken seriously, as engine startup idle quality and drivability may be both at risk. This is why this code is regarded as severe or serious.