What Does P1247 Mean?
DTC P1247 indicates the needle lift sensor circuit has an open circuit or is shorted to the positive voltage supply (B+). The sensor signal wire is reading at or near supply voltage when it should be producing a variable signal. This complete loss of valid needle lift data forces the PCM to use default injection timing values, degrading diesel engine performance.
Common Causes
30%
Open circuit in the needle lift sensor signal wire
25%
Sensor signal wire shorted to the 5V reference or 12V supply wire
20%
Failed needle lift sensor with open internal circuit
15%
Damaged connector at the needle lift sensor allowing cross-pin shorts
10%
Wiring harness damage near the injector due to heat exposure
Diagnostic Steps
1
Disconnect the needle lift sensor and measure the voltage on the signal wire at the PCM connector — if it reads near 5V or 12V, the PCM is pulling the line high due to an open circuit.
2
Check continuity of the sensor signal wire from the sensor connector to the PCM connector — an open indicates a broken wire.
3
Inspect for wiring damage or cross-shorts between the signal wire and the reference voltage wire in the harness, especially near the injectors where heat is extreme.
4
Measure the needle lift sensor resistance and compare to manufacturer specifications to verify sensor integrity.
5
Inspect the sensor connector for melted plastic, corroded pins, or spread terminals that could cause an intermittent open or short to B+.
Estimated Repair Cost
$200 - $900
Parts + labor, varies by vehicle and location
DTC P1247 indicates the needle lift sensor circuit has an open circuit or is shorted to the positive voltage supply (B+). The sensor signal wire is reading at or near supply voltage when it should be producing a variable signal. This complete loss of valid needle lift data forces the PCM to use defa...
The most common cause of P1247 (Needle Lift Sensor Circ. Open/Short to B+) is: Open circuit in the needle lift sensor signal wire
Typical repair costs for P1247 range from $200 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of needle lift sensor data forces the PCM to use estimated injection timing, which reduces power, increases emissions, and may cause rough running. The default timing strategy is conservative, reducing engine damage risk but noticeably affecting performance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1247 to identify the root cause.
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Quick Info
Category
Powertrain
System
Diesel Fuel Injection
Difficulty
Type
Manufacturer
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