P1345

Code

Generic P — Powertrain

SGC (Cam Position) Sensor Circuit Malfunction/ Crankshaft Position - Camshaft Position Correlation

Brand: Generic

Type: P — Powertrain

Views: UK: 33 EN: 100 RU: 42

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Page language: EN

Causes

Faulty camshaft position sensor (SGC)
Faulty crankshaft position sensor
Damaged sensor wiring or connectors (open, short to ground/voltage, corrosion)
Loose, stretched or jumped timing belt/chain or incorrect timing component installation
Damaged or missing teeth on cam/crank reluctor or tone wheel
Poor sensor power or ground

Symptoms

Check Engine Light (MIL) illuminated
Hard starting or no-crank/no-start in some cases
Rough idle, stalling, or intermittent misfires
Poor acceleration or reduced engine power
Possible failed emissions test or reduced fuel economy
Irregular or missing cam/crank signal when monitored

What to check

Read freeze-frame data and all stored related DTCs (look for P0016, P0335, P0340, P0341 etc.)
Visually inspect cam and crank sensor connectors and wiring for damage, corrosion, or loose pins
Check battery voltage and chassis/engine ground integrity
Monitor live cam and crank sensor signals with an advanced scan tool or oscilloscope while cranking and at idle
Measure sensor supply and ground at the connector (typically switched 5 V or battery reference depending on vehicle)
Check resistance and continuity of sensor circuits per manufacturer spec

Signal parameters

Camshaft sensor (Hall-type): 0–5 V square wave; one pulse per camshaft revolution (frequency proportional to RPM).
Camshaft sensor (VR-type): AC waveform; small mV at cranking, increases with RPM. Expect a clean consistent waveform without dropout.
Crankshaft sensor (Hall-type): 0–5 V square wave or pulled-up digital signal; multiple pulses per crank revolution depending on design.
Crankshaft sensor (VR-type): AC waveform amplitude typically from a few hundred mV at idle to several volts at higher RPM.
Phase relationship: cam pulse(s) should occur at the expected crank angle; correlation tolerances are vehicle specific — PCM flags when outside allowed window.

Diagnostic algorithm

Retrieve DTCs and freeze-frame data, note engine speed and conditions when fault set.
Visually inspect both cam and crank sensors, connectors, and wiring harnesses for physical damage, oil contamination, corrosion or loose pins.
Check battery voltage and main engine ground; poor supply/ground can distort sensor signals.
Backprobe sensor connectors. Verify sensor supply voltage and ground with key ON/crank per vehicle specifications.
Use an oscilloscope or advanced bi-directional scan tool to capture cam and crank waveforms while cranking and at idle. Confirm both sensors produce clean signals and verify phase/timing relationship.
If one sensor signal is missing or erratic, test continuity/resistance of the sensor circuit and replace the faulty sensor if out of spec.
If both sensors produce clean signals but correlation is incorrect, inspect timing components: check timing belt/chain alignment marks, tensioner condition, and sprocket/reluctor integrity for jumped teeth or damage.
Repair or replace damaged wiring, connectors, sensors, reluctors, or timing components as indicated. When sensors are replaced, clear codes and perform a test drive or re-learn procedure if required.
If fault remains after sensors, wiring, and timing verification, consider PCM diagnosis/repair or consult vehicle-specific service information for advanced diagnostics.

Likely causes

Wiring harness damage or connector corrosion at cam or crank sensor
Camshaft sensor failure (intermittent or out-of-spec output)
Timing belt/chain jumped one or more teeth or slipped
Reluctor/tone wheel damaged or misaligned
Weak ground or supply voltage to sensor causing distorted signal

Fault status

⚠️ Status

PCM reports camshaft position signal inconsistent with crankshaft position — cam/crank correlation outside allowable tolerance. MIL set; engine may exhibit misfire, rough running, or no-start depending on severity.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours