P1345 Camshaft / Crankshaft Position Sensor Correlation Fault

The P1345 trouble code indicates that the engine control module (ECM/PCM) has detected a correlation problem between the camshaft position signal and the crankshaft position signal.

The engine computer constantly compares these two signals to determine exactly where the crankshaft and camshaft are in their respective rotations. This information allows the ECM to control ignition, fuel injection, variable valve timing, and other engine functions at the correct moment.

When the signals do not have the expected relationship, P1345 may be stored.

This does not automatically mean that either position sensor has failed.

The sensors may be working correctly while the actual problem is caused by a stretched timing chain, incorrect timing, a damaged reluctor or trigger wheel, a VVT problem, wiring, poor electrical connections, or a mechanical timing issue.

Why Camshaft and Crankshaft Correlation Matters

The crankshaft and camshaft have to remain synchronized.

The crankshaft determines the position of the pistons, while the camshaft controls the opening and closing of the valves.

The ECM uses the crankshaft position sensor to determine crankshaft speed and position and uses the camshaft position sensor to determine which part of the four-stroke cycle the engine is in.

The computer expects the two signals to appear in a specific relationship.

If that relationship changes, the ECM may no longer be able to determine engine position with the required accuracy.

This can affect:

• Fuel injection timing

• Ignition timing

• Injector synchronization

• Variable valve timing

• Engine starting

• Idle quality

• Emissions

• Engine performance

P1345 Is a Synchronization Problem

It is useful to think of P1345 as a timing relationship problem, rather than simply a sensor problem.

The ECM is effectively asking:

“Do the camshaft and crankshaft signals occur where they should relative to each other?”

If the answer is no, the code can be triggered.

This can happen even when both sensors produce apparently normal signals.

For example, a timing chain may have stretched enough to move camshaft timing several degrees. Both sensors can still generate clean electrical signals, but those signals no longer have the correct relationship.

That is a very different problem from a completely failed camshaft sensor.

Common Causes of P1345

Incorrect mechanical timing

A timing chain or timing belt that has jumped one or more teeth can immediately change the relationship between the camshaft and crankshaft.

This can happen because of:

• Worn timing components

• A failed tensioner

• A damaged guide

• Incorrect previous timing-belt installation

• A loose timing component

• Excessive chain stretch

This is one of the most important possibilities to investigate.

Stretched timing chain

A worn timing chain can gradually alter camshaft timing.

The engine may continue to run, but the ECM may eventually detect enough deviation to set a correlation fault.

Chain-related problems may also produce rattling noises, especially during startup, although noise is not guaranteed.

Faulty camshaft position sensor

The camshaft sensor can produce an incorrect, weak, distorted, or intermittent signal.

The ECM may then calculate an incorrect camshaft position.

Faulty crankshaft position sensor

The same applies to the crankshaft sensor.

A distorted crankshaft signal can make the camshaft signal appear incorrectly synchronized even when the camshaft itself is mechanically positioned correctly.

Damaged reluctor or trigger wheel

Both position sensors rely on a physical target or reluctor pattern.

A damaged, cracked, bent, missing, or incorrectly positioned trigger wheel can produce a signal that does not match the expected pattern.

Variable Valve Timing problem

On engines equipped with VVT, the camshaft may be intentionally moved relative to the crankshaft.

The ECM knows when it has commanded this movement and expects the camshaft position to respond accordingly.

A sticking camshaft actuator, failed solenoid, restricted oil passage, low oil pressure, or incorrect oil condition can prevent the camshaft from reaching the commanded position.

This can result in a correlation-related fault.

Low or contaminated engine oil

Many VVT systems depend on engine oil pressure to move the camshaft phaser.

Low oil level, incorrect oil viscosity, sludge, or contaminated oil can interfere with camshaft positioning.

This is why an engine oil check can be relevant to P1345 even though the code itself concerns camshaft and crankshaft position.

Wiring or connector problems

The sensor circuits can be affected by:

• Broken wires

• Corroded terminals

• Loose connectors

• Short circuits

• Poor grounds

• Electrical interference

• Harness damage

An intermittent electrical problem can create an apparent synchronization problem.

Sensor installation problem

If a sensor has been recently replaced, incorrect installation, incorrect sensor type, excessive sensor-to-target clearance, or damage during installation should be considered.

ECM problem

An ECM fault is possible, but it is normally much less common than mechanical timing, VVT, sensor, reluctor, or wiring problems.

Symptoms of P1345

The symptoms can range from barely noticeable to severe.

Possible symptoms include:

• Check Engine Light

• Hard starting

• Long cranking

• Rough idle

• Engine misfire

• Hesitation

• Poor acceleration

• Reduced engine power

• Poor fuel economy

• Engine stalling

• Poor throttle response

• Irregular idle speed

• Reduced performance

• Crank-no-start

Some vehicles may enter a reduced-power or backup engine-control strategy when synchronization becomes unreliable.

When the Engine Will Not Start

A severe camshaft/crankshaft correlation problem can prevent the engine from starting.

The ECM needs reliable synchronization to know when fuel injection and ignition should occur.

If the signals are significantly out of position, the ECM may be unable to establish correct engine timing.

This is particularly suspicious if P1345 appears immediately after:

• Timing-chain work

• Timing-belt replacement

• Cylinder-head work

• Engine replacement

• Camshaft work

• Crankshaft work

If the engine was working normally before major timing-related repairs and P1345 appeared immediately afterward, mechanical timing and component installation should be checked before replacing sensors.

A Sensor Can Be Good Even When P1345 Is Present

This is one of the most important diagnostic points.

Imagine that both sensors produce clean electrical signals.

However, the timing chain has stretched and the camshaft is now slightly behind its expected position.

The ECM sees:

Crankshaft signal = valid

Camshaft signal = valid

Relationship between signals = incorrect

P1345 can therefore be set even though neither sensor is necessarily defective.

Replacing both sensors in this situation would not correct the underlying timing problem.

How P1345 Should Be Diagnosed

The diagnosis should establish whether the problem is electrical, mechanical, or related to variable valve timing.

Start With the Other Codes

Scan the vehicle for all stored and pending DTCs.

Look for codes relating to:

• Camshaft position

• Crankshaft position

• VVT

• Oil pressure

• Engine misfire

• Ignition

• Fuel injection

• Engine timing

A separate camshaft sensor circuit code, for example, could change the diagnostic direction considerably.

Look at Freeze-Frame Data

Freeze-frame information can help determine when the correlation fault occurred.

Useful information includes:

• Engine RPM

• Engine load

• Coolant temperature

• Vehicle speed

• Battery voltage

• Camshaft position

• Crankshaft position

• VVT commanded position

• VVT actual position

If the fault occurs only during starting, that may suggest a different problem from one that appears only under high RPM or engine load.

Compare Camshaft and Crankshaft Data

If the scan tool provides synchronization information, check whether the ECM reports:

• Cam/crank synchronization achieved

• Synchronization lost

• Camshaft actual position

• Camshaft commanded position

• Crankshaft position

• VVT target vs actual position

A correlation problem that appears immediately during cranking deserves particular attention.

Check the Sensors and Wiring

Inspect both the camshaft and crankshaft sensor circuits.

Look for:

• Damaged connectors

• Corrosion

• Loose terminals

• Broken wires

• Harness chafing

• Oil contamination

• Poor sensor installation

Both sensors should have the correct power, ground, and signal characteristics according to the manufacturer's wiring diagram.

Use an Oscilloscope When Necessary

An oscilloscope can be extremely valuable with P1345.

Instead of simply checking whether a sensor produces a signal, the technician can observe the relationship between the camshaft and crankshaft waveforms.

This can reveal:

• Missing pulses

• Distorted waveforms

• Intermittent signals

• Incorrect signal amplitude

• Damaged reluctor patterns

• Timing-chain-related phase changes

• Cam/crank synchronization errors

Comparing the actual waveform with a known-good pattern can be much more informative than simply measuring sensor resistance.

Check Mechanical Timing

If the electrical signals appear normal but the correlation remains incorrect, mechanical timing becomes a major suspect.

Depending on the engine, this may require checking:

• Timing-chain alignment

• Timing-belt alignment

• Camshaft timing marks

• Crankshaft timing position

• Chain tension

• Chain guides

• Camshaft phasers

• Reluctor-wheel position

If the engine uses a timing chain with significant wear, checking only the visible timing marks may not be enough to identify every problem.

VVT Can Create a False Impression of Mechanical Timing Failure

Modern engines frequently use variable valve timing.

The camshaft is intentionally moved relative to the crankshaft under different operating conditions.

If the VVT system cannot control that movement correctly, the ECM may see an unexpected cam/crank relationship.

Possible causes include:

• Sticking VVT solenoid

• Restricted oil passage

• Low oil pressure

• Incorrect oil viscosity

• Sludge

• Failed camshaft phaser

• Mechanical phaser wear

• Wiring problem

• Incorrect commanded position

Therefore, P1345 should not automatically lead to timing-chain replacement.

Check Engine Oil Before Blaming VVT Components

If the engine uses oil-controlled VVT, checking the oil is a relatively simple and valuable diagnostic step.

Verify:

• Oil level

• Correct viscosity

• Correct specification

• Oil condition

• Evidence of contamination

• Appropriate oil pressure

A VVT system can behave incorrectly simply because it cannot obtain the oil pressure or flow required to move the camshaft actuator.

Timing Chain Stretch vs Sensor Failure

The symptoms can overlap.

A sensor problem may produce:

• Intermittent starting

• Sudden stalling

• Erratic engine operation

• Signal dropouts

• Correlation faults

A timing-chain problem may produce:

• Progressive starting difficulty

• Rough running

• Reduced performance

• Correlation faults

• Abnormal chain noise

• Persistent camshaft timing deviation

Live data and waveform analysis can help distinguish these conditions.

P1345 After Timing-Belt or Chain Replacement

This deserves special attention.

If P1345 appeared immediately after timing-related work, verify the mechanical timing before replacing sensors.

Possible causes include:

• Timing marks not aligned correctly

• Incorrect belt/chain installation

• Incorrect tension

• Incorrect camshaft position

• Reluctor or trigger-wheel installation error

• Damaged wiring during the repair

• Incorrect sensor installation

A correlation code that appears immediately after such work should not be treated as an unrelated coincidence.

P1345 and Misfire Codes

A cam/crank synchronization problem can cause engine misfires.

If valve timing or injection/ignition timing is incorrect, combustion can occur at the wrong point in the cycle.

Therefore, P1345 may appear together with cylinder-specific misfire codes.

The misfire does not necessarily mean the ignition coil, spark plug, or injector is the primary problem.

The underlying synchronization problem should be addressed first.

Can P1345 Damage the Engine?

The code itself does not mean engine damage has occurred.

However, the cause can potentially be serious.

If a timing chain or belt has jumped significantly, valve timing may be far enough out of position to create serious running problems.

On an interference engine, a major timing failure can potentially allow pistons and valves to contact each other.

For that reason, a vehicle with severe P1345 symptoms—especially sudden loss of power, unusual timing-chain noise, or a no-start condition—should not simply be repeatedly cranked or driven until the mechanical timing has been evaluated.

Can You Drive With P1345?

It depends on how the engine is behaving.

A vehicle with a steady Check Engine Light and normal operation may still be driveable for a short distance to a repair facility.

However, driving should be avoided if there is:

• Severe engine shaking

• Repeated stalling

• Major power loss

• Difficult starting

• Abnormal timing-chain noise

• Backfiring

• A flashing Check Engine Light

If mechanical timing has shifted, continuing to operate the engine may make the situation considerably worse.

Possible Repairs

The repair depends on the actual cause.

Possible repairs include:

• Replacing a faulty camshaft position sensor

• Replacing a faulty crankshaft position sensor

• Repairing sensor wiring

• Repairing connectors

• Correcting sensor installation

• Repairing or replacing a damaged reluctor

• Correcting timing-chain alignment

• Replacing a stretched timing chain

• Replacing a damaged timing belt or related components

• Replacing a timing-chain tensioner or guide

• Repairing a VVT solenoid

• Replacing a camshaft phaser

• Correcting engine oil level or specification

• Repairing an oil-pressure problem

• Repairing the ECM only after the other possibilities have been eliminated

P1345 Is Not Simply a “Bad Sensor” Code

The most useful way to approach P1345 Camshaft / Crankshaft Position Sensor Correlation Fault is to think about synchronization.

The ECM has two important pieces of information:

Where is the crankshaft?

Where is the camshaft relative to the crankshaft?

If both sensors provide valid signals but those signals no longer have the expected relationship, the ECM can set P1345.

That makes the code particularly valuable as a warning about engine timing, not just sensor electronics.

A proper diagnosis should therefore move from the electrical side to the mechanical side:

Check the sensors and wiring → verify the signals → compare cam/crank synchronization → check VVT operation → verify mechanical timing.

Only after those areas have been confirmed should major components such as the ECM be considered.

In other words, P1345 tells you that the engine computer has lost confidence in the relationship between camshaft position and crankshaft position. Finding out why that relationship is wrong is the real diagnosis.