What Does P1338 Mean?
P1338 indicates that the camshaft position sensor on bank 1 has an open circuit or a short to the positive voltage supply. The CMP sensor is essential for sequential fuel injection and variable valve timing control. This fault prevents the ECU from determining camshaft rotational position on bank 1, typically causing the engine to default to batch-fire injection mode.
Safety Warning
Loss of the bank 1 CMP signal forces the engine into a degraded injection mode with reduced performance and efficiency. Variable valve timing on bank 1 will be disabled, which may also affect idle quality and emissions.
Common Causes
30%
Failed camshaft position sensor (internal open circuit)
25%
Broken wire in the CMP sensor harness creating an open circuit
20%
Wiring short to battery voltage from chafed insulation contacting a power wire
15%
Corroded or damaged CMP sensor connector
10%
ECU CMP sensor input circuit failure
Diagnostic Steps
1
Disconnect the CMP sensor bank 1 connector and measure sensor resistance. Compare to specification (typical Hall-effect sensors have specific impedance ranges).
2
With the sensor disconnected, check for voltage at the ECU side of the harness connector. If battery voltage is present on the signal wire, trace the harness for a short to B+.
3
Perform a continuity check on each wire from the sensor connector to the ECU connector. An open reading indicates a broken wire.
4
Inspect the harness routing near the valve cover, timing cover, and any areas where wires may contact hot or moving parts.
5
If wiring is intact and the sensor tests bad, replace the CMP sensor bank 1 and clear codes.
6
After repair, verify proper CMP signal with a scan tool or oscilloscope and confirm sequential injection operation is restored.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
P1338 indicates that the camshaft position sensor on bank 1 has an open circuit or a short to the positive voltage supply. The CMP sensor is essential for sequential fuel injection and variable valve timing control. This fault prevents the ECU from determining camshaft rotational position on bank 1,...
The most common cause of P1338 (CMP Sensor Bank 1 Open Circuit Or Short To Positive) is: Failed camshaft position sensor (internal open circuit)
Typical repair costs for P1338 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of the bank 1 CMP signal forces the engine into a degraded injection mode with reduced performance and efficiency. Variable valve timing on bank 1 will be disabled, which may also affect idle quality and emissions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1338 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Position Sensing / Variable Valve Timing
Difficulty
Type
Manufacturer
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