Description of the P0338 fault code.
OBD2 Error Codes

P0338 Crankshaft Position Sensor “A” Circuit High High

26.05.2022 /

P0338 – OBD-II Trouble Code Technical Description

Trouble code P0338 indicates that the PCM has detected too high voltage in the crankshaft position sensor A circuit.

What does the fault code mean P0338?

Trouble code P0338 indicates a high signal problem in the crankshaft position A (CKP) sensor circuit, which is detected by the ECM (engine control module). This may indicate that the CKP sensor or related components are producing too high a voltage outside of the normal range.

Fault code P0338.

Possible reasons

Some possible reasons for the P0338 trouble code:

  • Crankshaft position (CKP) sensor malfunction: The CKP sensor itself may be damaged or malfunctioning, resulting in a high signal level.
  • Incorrect position of the CKP sensor: If the CKP sensor is not installed correctly or its position does not meet the manufacturer's standards, it may cause a high level signal.
  • Problems with wiring or connectors: Damaged or shorted wires, or oxidized or burnt connectors in the CKP sensor circuit can cause a high signal level.
  • Problems with the ECM (Engine Control Module): Faults in the ECM itself can also result in an erroneously high signal level.
  • Electrical interference: Electrical noise in the CKP sensor circuit can cause signal distortion and cause P0338 to appear.
  • Crankshaft problems: Defects or damage on the crankshaft itself can cause the CKP sensor to read incorrectly and therefore cause a high signal level.
  • Malfunctions in other components of the ignition or fuel injection system: Some problems with other engine components, such as the distributor sensor, can also affect the performance of the CKP sensor and cause the P0338 code.

These are just some of the possible causes of the P0338 code, and additional diagnostic procedures may be required to accurately diagnose and correct the problem.

What are the symptoms of a fault code? P0338?

Some possible symptoms that may occur with DTC P0338:

  • Difficulty starting the engine or improper operation of the engine: A high signal level in the crankshaft position sensor circuit can lead to difficulty starting the engine or improper idling.
  • Loss of power: Incorrect signals from the CKP sensor may result in loss of engine power, especially under load.
  • Unstable idle: If the CKP sensor does not detect the crankshaft position correctly, it may cause rough idle or even skipping.
  • Increased fuel consumption: Improper operation of the CKP sensor may result in improper fuel delivery, which may cause increased fuel consumption.
  • The Check Engine light comes on: When trouble code P0338 occurs, the ECM activates the Check Engine Light (or MIL) to alert the driver that there is a problem with the engine management system.

These symptoms may occur to varying degrees and may vary depending on the specific cause of the error and the type of engine.

How to diagnose a fault code P0338?

To diagnose DTC P0338, the following steps are recommended:

  1. Checking for errors using an OBD-II scanner: Use an OBD-II scanner to read error codes as well as check other engine parameters such as sensor data and control system operating modes.
  2. Checking wiring and connectors: Check the wiring and connectors connecting the crankshaft position (CKP) sensor to the engine control module (ECM). Make sure the wires are intact and securely connected, and there are no signs of corrosion or oxidation.
  3. Checking the resistance of the CKP sensor: Measure the resistance of the CKP sensor using a multimeter. Check that the resistance is within the range specified in the manufacturer's technical documentation.
  4. Checking the CKP sensor voltage: Measure the voltage at the output of the CKP sensor when starting the engine. Make sure the voltage is within the acceptable range.
  5. Checking the position of the CKP sensor: Make sure the CKP sensor is installed correctly and its position meets the manufacturer's specifications.
  6. Additional diagnostics: If necessary, perform additional diagnostic procedures, such as checking the power and ground circuits, and checking other engine management system components that may affect the operation of the CKP sensor.

After completing these steps, you can more accurately determine the cause of the P0338 trouble code and begin the necessary repairs or replacement of components. If you are unsure of your diagnostic or repair skills, it is best to contact a qualified auto mechanic.

Diagnostic errors

When diagnosing DTC P0338, the following errors may occur:

  • Misinterpretation of symptoms: Some symptoms, such as rough engine operation or starting problems, may be related to other engine components, not just the crankshaft position (CKP) sensor. Misinterpretation of these symptoms may lead to misdiagnosis.
  • Incorrect checking of wiring and connectors: Failure to pay sufficient attention to checking wiring and connectors may result in missing detection of a problem if the problem actually lies with these components.
  • Insufficient diagnostics of other components: Since problems with the CKP sensor can be caused by factors other than a faulty CKP sensor, failure to properly diagnose other engine management system components may result in improper repair or replacement of components.
  • Interpreting incorrect test results: Incorrect interpretation of test results such as CKP sensor resistance or voltage measurements can lead to misdiagnosis and replacement of unnecessary components.
  • Skipping additional diagnostic steps: Failure to perform additional diagnostic procedures, such as checking the power and ground circuits, or checking other engine management system components, may result in an incomplete diagnosis of the problem.

All of these errors can lead to incorrect diagnosis and, as a result, incorrect repair or replacement of components. Therefore, it is important to carefully monitor each diagnostic step and consult the manufacturer’s documentation or qualified specialists if necessary.

How serious is the fault code? P0338?

Trouble code P0338 indicates problems with the crankshaft position (CKP) sensor, which plays an important role in engine performance. While symptoms may vary depending on the specific cause of the error, in general it can lead to the following serious problems:

  • Loss of power and engine instability: Improper operation of the CKP sensor may result in loss of engine power as well as rough operation, which may affect the overall performance of the vehicle.
  • Incorrect engine starting: Incorrect signals from the CKP sensor may cause difficulty starting the engine or even complete inability to start the engine.
  • Increased fuel consumption and emissions of harmful substances: Improper engine operation due to problems with the CKP sensor can lead to increased fuel consumption and increased emissions of harmful substances.
  • Engine damage: If serious problems with the CKP sensor are not detected and corrected, engine damage may occur due to improper fuel injection and ignition timing management.

Therefore, code P0338 should be taken seriously as it can cause serious problems with engine performance and vehicle safety. If this code appears, it is recommended that you immediately contact a qualified auto mechanic to diagnose and repair the problem.

What repair will help eliminate the code? P0338?

Troubleshooting the P0338 trouble code may require several steps depending on the cause of the problem:

  • Replacing the Crankshaft Position (CKP) Sensor: If the CKP sensor is faulty or its signals are not being read correctly, the sensor must be replaced. After replacement, test to ensure that the new sensor is working properly.
  • Checking and updating ECM software: Sometimes the P0338 code may be caused by a problem in the ECM software. Check if a software update is available from the vehicle manufacturer and update the ECM if necessary.
  • Checking wiring and connectors: Perform additional checks on the wiring and connectors connecting the CKP sensor to the Engine Control Module (ECM). Make sure the wires are intact, securely connected and there are no signs of corrosion or oxidation. If necessary, repair or replace damaged components.
  • Diagnostics of other engine management system components: Incorrect operation of the CKP sensor can be caused not only by its own malfunction, but also by problems with other components of the engine management system. Perform additional diagnostics to rule out problems with other components.
  • Checking the presence of a signal from the CKP sensor: Check whether the signal is received from the CKP sensor to the ECM. If there is no signal, the problem may lie in the electrical circuit or in the sensor itself. Carry out the necessary repairs.

After the appropriate repairs or component replacements have been made, it is recommended that the error code be cleared from the ECM and a test drive performed to ensure that the problem has been resolved. If you are unsure of your skills or do not have the necessary equipment, it is better to contact a qualified auto mechanic.

How to Fix P0338 Engine Code in 2 Minutes [1 DIY Method / Only $9.55]

P0338 – Brand-specific information

Trouble code P0338 can occur in various makes of cars, some of them are:

This is just a small list of car brands where this fault code may occur. Specific details and causes may vary depending on the model and year of the vehicle.

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