Failed crankshaft position sensor (internal winding short or open circuit); Damaged or chafed sensor wiring harness near the exhaust manifold or accessory belt; Corroded or loose connector pins at the crank sensor or ECM; Excessive air gap between the sensor tip and the reluctor wheel due to worn sensor mount or debris; Damaged or missing teeth on the crankshaft reluctor wheel; Poor engine ground or voltage drop on the sensor's reference circuit; Rarely, an internal ECM fault on the crank signal input circuit

DTC codes / Jaguar codes / P1245

P1245 · JaguarCrank Signal Low Input

Q: What does code P1245 mean?

Crank Signal Low Input. P1245 on a Jaguar means the engine control module (ECM) has detected an abnormally low voltage on the crankshaft position sensor signal circuit, so the ECM cannot reliably determine engine speed and position. The ECM stores this code when the crank signal amplitude or duty cycle falls below the expected threshold during cranking or running.

P1245 on a Jaguar means the engine control module (ECM) has detected an abnormally low voltage on the crankshaft position sensor signal circuit, so the ECM cannot reliably determine engine speed and position. The ECM stores this code when the crank signal amplitude or duty cycle falls below the expected threshold during cranking or running.

SystemPowertrain

Code typeJaguar specific

SeverityHigh

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Engine cranks but will not start, or starts only after long cranking
Intermittent stalling, especially when the engine is hot or after hitting a bump
Rough running or misfire because the ECM loses accurate crank position
Tachometer drops to zero or fluctuates erratically while driving
Often no symptoms besides the warning light if the fault is intermittent
Reduced power or limp-home mode triggered by the ECM when the signal is lost

Common causes, most likely first

Failed crankshaft position sensor (internal winding short or open circuit)
Damaged or chafed sensor wiring harness near the exhaust manifold or accessory belt
Corroded or loose connector pins at the crank sensor or ECM
Excessive air gap between the sensor tip and the reluctor wheel due to worn sensor mount or debris
Damaged or missing teeth on the crankshaft reluctor wheel
Poor engine ground or voltage drop on the sensor's reference circuit
Rarely, an internal ECM fault on the crank signal input circuit

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm P1245 is active and not a ghost code from a low battery
Inspect the crank sensor connector and harness for corrosion, chafing, or oil contamination, and repair as needed
Measure sensor resistance and compare to Jaguar specification, then check the air gap to the reluctor wheel
Back-probe the signal wire at the ECM and observe the crank waveform on an oscilloscope while cranking
Check the reluctor wheel for missing teeth, cracks, or excessive runout through the sensor hole
Perform a voltage drop test on the sensor ground and reference circuits to rule out wiring resistance
Replace the crankshaft position sensor with a known-good unit and clear the code, then verify the signal returns

Crank signal faults that fool good technicians

A weak battery or slow cranking can set P1245 because the ECM sees low signal amplitude during cranking, so always load-test the battery before condemning the sensor.
The crank sensor on many Jaguar V6 and V8 engines sits close to the exhaust manifold, and heat-soak damage to the sensor or its wiring often only shows up when the engine is hot.
An intermittent P1245 that clears after restart is frequently caused by a chafed signal wire grounding against the block rather than a failed sensor.
Aftermarket crank sensors for Jaguars have a poor reputation for signal quality, so a new but cheap sensor can set the same code again.
A failing camshaft sensor or a stretched timing chain can cause the ECM to misreport crank signal faults, so check cam-crank correlation before replacing parts.

Can I keep driving with P1245?

Do not drive the car if it is stalling or will not restart reliably, because a sudden loss of crank signal can cut the engine at speed. If the light is on but the engine runs normally, drive only to a workshop and avoid heavy load or high-speed driving.

Tools that help

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Guidance is general and written for Jaguar vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.