P1340
FordCamshaft Position Sensor B Circuit Malfunction
The PCM has detected a problem with the electrical signal from camshaft position sensor B. The sensor reports camshaft position so the PCM can coordinate engine operation. A circuit fault can disrupt that information, but the code does not prove the sensor itself has failed. Effects depend on the vehicle and engine.
⚠️ Before You Begin (Safety First)
If the engine stalls, runs severely rough, or becomes difficult to control, stop driving when it is safe and arrange diagnosis. If it runs normally, have the fault checked promptly; do not ignore worsening symptoms.
Common Symptoms
- The check-engine light may be on, with no noticeable change in how the engine runs.
- Hard starting or failure to start may occur if the PCM cannot use a reliable camshaft position signal.
- Rough running, hesitation, reduced performance, or stalling may occur if the signal disruption affects engine operation.
- Symptoms can be intermittent if a connector or wire makes unreliable contact.
Common Causes
- A fault within camshaft position sensor B or its signal may disrupt the PCM's camshaft position information.
- A loose, damaged, corroded, or contaminated sensor connector can interfere with the circuit.
- Damaged, chafed, or open wiring, or an unintended short in the circuit, can affect the signal.
- A power or ground problem affecting the sensor circuit may prevent a usable signal.
- A fault elsewhere affecting the camshaft signal, such as a related mechanical or signal-target issue, may need investigation if the sensor circuit checks out.
Diagnostic Steps
- Note whether the engine starts and runs normally, and record any stalling, rough running, or starting problems; these details help assess urgency.
- With the engine off and cool, visually check the accessible sensor B connector and nearby wiring for looseness, damage, corrosion, or rubbing. Do not pull on wires or disconnect components with the engine running.
- Check for other stored diagnostic codes and record them before clearing anything; related codes can help guide diagnosis.
- If the fault returns or symptoms occur, arrange circuit and signal testing using service information for the exact model, year, and engine. Do not replace the sensor based on this code alone.
When to Call a Professional
Read all stored codes and review available camshaft-related scan data before replacing parts. Inspect the sensor connector and wiring, then test the circuit and sensor signal using the correct vehicle wiring information and service procedure. Consider other signal or engine-timing faults if circuit checks do not identify the cause.
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Commonly Asked Questions
Does P1340 prove camshaft position sensor B is bad?
No. It identifies a malfunction in the sensor B circuit, which may involve the sensor, wiring, connector, power or ground, or another issue affecting the signal.
Can I keep driving with P1340?
If the engine runs normally, arrange diagnosis promptly and watch for changes. Stop driving when safe if it stalls, runs severely rough, or becomes difficult to control.
Why might the code return after replacing the sensor?
The wiring, connector, power or ground, or another part of the camshaft signal path may still be faulty. The circuit should be tested before another part is replaced.
Can P1340 cause a no-start?
It can, depending on how the signal fault affects engine operation on that vehicle. A no-start can have other causes, so further diagnosis is needed.
Browse Available Code Guides
Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.