🔢
P0338 typically means the sensor signal line is open or shorted to power. An open sensor element pulls the signal up to full reference voltage. Test the sensor at the connector before pulling it out of a hard-to-reach location. See top-rated scanners on Amazon ↗
🗺️ Where Is the Problem?
Blueprint view - P0338 affects engine sensors and management circuits
These are statistical causes across ALL vehicles - your exact car may rank differently
For example, on a Honda 4-cyl the downstream O2 sensor causes P0338 64% of the time, but on a GM 5.3L V8 the catalytic converter is the cause 71% of the time. Get a probability ranking built specifically for your year, make, model, and mileage.
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🎯 Top Causes & Probability
55%
#1 - Most Likely
Failed Crank Sensor (Open Internally)
The Hall-effect sensor has gone open inside, so the signal line floats to its pull-up voltage. Engine cranks but won't start, or starts and dies. Replacement of the sensor cures it.
🔨 Part
$25–$120
👨🔧 Labor
$50–$200
⚡ DIY Difficulty
Medium
30%
#2 - Check First
Wiring Shorted to Power
A chafed signal wire touching the 12V or 5V harness pins the signal high. Hunt for melted insulation along the harness path, especially near the starter and engine block.
🔨 Part
$10–$60
👨🔧 Labor
$60–$160
⚡ DIY Difficulty
Medium
10%
#3 - Less Common
PCM Signal Pull-Up Issue (Rare)
A failing internal pull-up resistor in the PCM can pin the input high even with a good sensor. Confirm by testing the sensor directly - if it produces a normal AC pulse, suspect the PCM.
🔨 Part
$300–$1,000
👨🔧 Labor
$100–$250
⚡ DIY Difficulty
Hard
🚗 Most Affected Vehicles
🚫 Is It Safe to Drive?
No - the vehicle may stall or refuse to start. Treat as a tow-it-home situation if it leaves you stranded.
🔧 Step-by-Step Diagnosis
- Disconnect the Sensor and Check Voltage at the Harness - With the key on and sensor unplugged, the signal pin should sit near reference voltage. If it stays pegged high, look for a wiring short to power.
- Test Sensor with a Multimeter - For Hall-effect sensors, key on and rotate the engine by hand. Voltage should pulse between near 0V and near 5V. If it stays high, the sensor is bad.
📍 Find a Trusted Shop Near You
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Tips for Choosing a Shop
- Ask if they charge a diagnostic fee and whether it applies toward the repair
- Request a written estimate before approving any work
- Ask specifically about the part brand - OEM vs. aftermarket matters for this code
- Check Google reviews for recent mentions of the specific repair you need