The P0338: Crankshaft Position Sensor A Circuit High Input code indicates that the engine control module (ECM) is detecting a higher-than-expected input signal from the crankshaft position sensor A. This sensor monitors the position and speed of the crankshaft, providing vital information for timing and fuel injection. A high input signal suggests that the sensor may be malfunctioning, or there could be issues with the wiring or circuitry.
P0338 – Quick Overview
Meaning | P0338: Crankshaft Position Sensor A Circuit High Input |
Is it serious? | Yes, this code can cause poor engine timing, leading to performance issues like misfires, rough idling, or stalling. |
Possible causes | – Faulty crankshaft position sensor – High input signal – Circuit issues |
How to diagnose? | – Test sensor input – Inspect circuit and wiring – Replace crankshaft position sensor if needed |
P0338 Meaning
The P0338: Crankshaft Position Sensor A Circuit High Input code means that the ECM is receiving a higher-than-expected signal from crankshaft position sensor A. This sensor is essential for monitoring the crankshaft’s speed and position, which helps the ECM manage timing and fuel injection. A high input signal can cause the ECM to misinterpret engine timing, resulting in engine performance issues such as misfires, poor fuel efficiency, or stalling.
Step-by-step diagnostic guide
Follow the steps below to diagnose and resolve the P0338 code by addressing potential causes one by one.
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for additional related codes that may provide further insight into the issue. | OBD-II Scanner |
Inspect the Crankshaft Position Sensor A | Visually inspect the sensor for signs of damage, wear, or corrosion. Ensure it is properly mounted and connected securely. | Flashlight, Safety Gloves |
Test Crankshaft Position Sensor Input Signal | Use a multimeter to test the input signal from the crankshaft position sensor A. Compare the readings to the manufacturer’s specifications to ensure it is within the expected range. | Multimeter, Manufacturer’s Specifications |
Inspect Circuit and Wiring | Inspect the wiring and circuitry related to crankshaft position sensor A for any signs of damage, loose connections, or corrosion. Repair or replace damaged components as necessary. | Flashlight, Wiring Repair Kit |
Replace the Sensor if Necessary | If the crankshaft position sensor is faulty or producing a high signal, replace it with a new one to restore proper function. | Replacement Crankshaft Position Sensor, Safety Gloves |
Clear the Code and Test Drive | After completing repairs, clear the P0338 code using an OBD-II scanner. Test drive the vehicle to ensure the issue has been resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
Recheck for Codes | After the test drive, re-scan the vehicle to confirm that the P0338 code has not returned. If the code reappears, further diagnosis may be necessary. | OBD-II Scanner |
This diagnostic guide will help you resolve the P0338 code by ensuring the crankshaft position sensor A is functioning correctly, allowing the ECM to manage engine timing and performance effectively.

Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)