Your camshaft position sensor helps the engine computer know exactly
what the engine is doing. When it begins to fail, that small sensor
can cause starting problems, poor performance and a Check Engine Light.
Very important. The camshaft position sensor monitors
the position and movement of the camshaft and sends that information
to the engine control module, or ECM.
The computer uses this information along with data from the crankshaft
position sensor and other engine sensors to help control fuel injection,
ignition timing and overall engine operation.
When the signal is missing, intermittent or inaccurate, the computer
may have difficulty determining exactly where the engine is in its
operating cycle. That's when drivability problems can begin.
MonitorsCamshaft Position
Reports ToEngine Computer
Can TriggerCheck Engine Light
Important ForEngine Timing
What Does a Camshaft Position Sensor Do?
Think of the sensor as one of the engine computer's sets of eyes.
It helps the computer understand the position of internal engine
components while the engine is running.
Tracks Camshaft Position
The sensor detects the position of the camshaft as it rotates, giving
the engine computer information it needs to identify the engine's
operating cycle.
Supports Fuel Injection
On many engines, camshaft position information helps the computer
determine when fuel should be delivered to individual cylinders.
Works With the Crank Sensor
Camshaft and crankshaft position information can be compared by the
engine computer to monitor engine position and synchronization.
Helps Engine Management
Accurate sensor information helps the computer manage engine operation,
starting, performance and emissions-related systems.
Symptoms of a Bad Camshaft Position Sensor
A failing sensor doesn't always quit instantly. Some begin producing
an intermittent or unreliable signal, which can make the symptoms
come and go.
⚠ Check Engine Light
The engine computer may store a diagnostic trouble code when it
detects a camshaft position sensor circuit or timing-related problem.
🔑 Hard Starting
The engine may crank longer than normal before starting because the
computer is having difficulty determining engine position.
🚗 Rough Running
An unreliable signal can sometimes contribute to rough operation,
hesitation or inconsistent engine performance.
⬇ Loss of Power
Some vehicles may enter a reduced-performance strategy when the
computer detects an important engine-management fault.
🛑 Stalling
An intermittent sensor or wiring problem may contribute to an engine
stall, especially if the computer temporarily loses the signal.
⛽ Poor Fuel Economy
Engine-management problems can sometimes reduce efficiency, although
poor fuel economy alone does not prove that the camshaft sensor is bad.
Don't Replace the Sensor Just Because There's a Code
This is one of the most important things to remember when diagnosing
modern vehicles.
A Trouble Code Is a Starting Point — Not a Parts Order
A camshaft-related diagnostic code does not automatically mean
the camshaft position sensor itself has failed.
The problem could involve the electrical connector, damaged wiring,
poor voltage or ground, timing components, a reluctor or trigger wheel,
oil contamination, or another engine-management issue.
Diagnose the system before replacing parts whenever possible.
Common Camshaft Sensor Trouble Codes
Exact codes and definitions vary by vehicle and engine. However,
camshaft position sensor problems are commonly associated with codes
in the P0340 family.
P0340Camshaft position sensor circuit-related fault
P0341Camshaft position sensor range/performance-related fault
Vehicles with multiple cylinder banks or multiple camshafts may use
terms such as Bank 1, Bank 2, Sensor A and
Sensor B. Always verify the manufacturer's definition
for your specific year, make, model and engine before buying a sensor.
Before You Replace the Camshaft Sensor
A little diagnosis can save you from buying a part you didn't need.
Start with the basics.
1
Scan for Trouble Codes
Use an OBD-II scan tool to retrieve stored and pending codes. Record
them before clearing anything.
2
Inspect the Connector
Look for a loose plug, damaged locking tab, corrosion, oil intrusion,
bent terminals or other obvious connector problems.
3
Inspect the Wiring
Check the harness for rubbing, melted insulation, broken wires or
damage near hot and moving engine components.
4
Verify the Correct Sensor
Some engines use more than one camshaft position sensor. Confirm the
location and sensor designation before removing anything.
5
Follow Vehicle-Specific Testing
Electrical testing procedures and specifications vary. A service
manual or reliable repair-information source can provide the proper
test procedure for your vehicle.
Can You Replace a Camshaft Position Sensor Yourself?
Sometimes. On some vehicles the sensor is easy to reach and replacement
is relatively straightforward. On others it may be buried beneath
engine components or located in a difficult area.
DIY-Friendly Situations
The sensor is clearly accessible, you have identified the correct
sensor, you understand the connector and fastener arrangement, and
you have reliable specifications for the vehicle.
When to Call a Professional
Consider professional diagnosis when the fault is intermittent,
multiple timing codes are present, wiring needs electrical testing,
or the sensor is difficult to access.
Before Installing the New Sensor
Compare the replacement part with the original. Check the connector,
mounting position and sealing O-ring if equipped. Follow the proper
fastener torque and installation procedure for your engine.
Camshaft Sensor vs. Crankshaft Sensor
The names sound similar because both sensors help the computer
understand what's happening inside the engine — but they monitor
different rotating components.
Camshaft Position Sensor
Monitors camshaft position and helps the computer identify valve-train
and cylinder-cycle information used by the engine-management system.
Crankshaft Position Sensor
Monitors crankshaft position and speed, providing critical information
about engine RPM and crankshaft location.
The CarDudes Sensor Rule
Diagnose first. Replace second. A $30, $50 or $100
sensor isn't inexpensive if the original sensor wasn't the problem.
Check the code, connector and wiring before firing the parts cannon.
Keep Your Car Running Right
More practical CarDudes guides for maintaining your vehicle and
preventing expensive surprises.
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Simple maintenance habits that can help prevent unnecessary repairs
and keep more money in your pocket.
