P0345 Code: Subaru Impreza (2017-2023) - Causes, Symptoms & Fixes

P0345 Diagnostic Guide for 2017-2023 Subaru Impreza

Note: The data provided for this guide includes: No NHTSA owner complaints found for this make/model/year/issue combination, and No recalls found in NHTSA database. Data limitations mean this guide focuses on general, widely applicable diagnostic steps for P0345 on the 2017-2023 Impreza, with Subaru-specific considerations where relevant. No recalls found in NHTSA database.

CODE MEANING AND SEVERITY

• What the code means:
  • P0345 = Camshaft Position Sensor A Circuit Bank 1 (or Bank 1A) – Signal not detected or out of range for the camshaft position sensor designated as “A” on Bank 1.
  • In practical terms, the PCM/ECU isn’t seeing a valid camshaft synchronizing signal from the Bank 1 Camshaft Position Sensor (CPS) circuit, which can affect ignition timing and fuel injection timing.
• Severity and typical vehicle behavior:
  • MIL/Check Engine Light is usually illuminated.
  • Engine may run poorly, misfire, hesitate, or stall; starting may be difficult or impossible if the signal is completely absent.
  • In many cases the car may enter a limp mode to protect the engine.
  • Driving with this code long-term can increase exhaust emissions and reduce fuel economy; continued operation without repair can lead to more damage (e.g., misfires, catalytic converter strain).
• Important notes for Subaru Impreza:
  • Subaru boxer engines (like the Impreza 2.0L) use camshaft position sensors for each bank or cam train. Bank numbering and sensor labeling can vary by engine code and model year. For P0345 on these cars, Bank 1 is the sensor labeled as “A” on the Bank 1 side. Always confirm with the service manual specific to your engine code (e.g., FA20/FB20 variants) to map the exact sensor location.

COMMON CAUSES ON SUBARU IMPREZA

• Faulty Camshaft Position Sensor A (Bank 1)
  • The sensor itself fails or its internal circuitry degrades (aging, contamination, or moisture).
• Damaged or corroded wiring/connectors
  • Harness abrasion, pin damage, loose or corroded connectors, or oil/water intrusion at the CPS connector.
• Faulty 5V reference or ground to the CPS circuit
  • A weak or intermittent supply/ground can cause erratic sensor readings.
• Timing issue (cam timing out)
  • Timing chain/belt wear, chain tensioner or guides failure, or improper timing alignment can cause the cam sensor signal to be out of expected range.
• Oil contamination or sludge around the cam gear or sensor
  • Oil leaks from the valve cover area can coat the sensor or connector and affect readings.
• PCM/ECU or software fault
  • Rare, but possible; a software/firmware issue can misinterpret a good signal or misreport a circuit fault.
• Aftermarket modifications or poor repairs
  • Wiring mods, sensor replacements of questionable quality, or damaged aftermarket parts can trigger this code.
• Crankshaft position sensor interaction
  • A bad crank sensor (P0335, etc.) or misreadings can sometimes be accompanied by cam sensor codes or create cascading timing signals issues.

SYMPTOMS

• Check Engine Light (MIL) illuminated.
• Misfires, rough idle, or hesitation during acceleration.
• Reduced power or “limp mode” in certain situations.
• Hard to start or no-start conditions (especially if cam signal is completely absent or intermittent).
• Decreased fuel economy.
• Possible drive-cycle or cold-start sensitivity (signal may degrade more when the engine is cold or hot, depending on the fault).

DIAGNOSTIC STEPS

Tools needed: OBD-II scanner, multimeter, service manual/wiring diagram for your engine code, possibly an oscilloscope, basic hand tools, backprobe connectors.

Step-by-step process:

Confirm the code and context

• Use a capable OBD-II scanner to confirm P0345 and check for related codes (P0340, P0341, P0335, etc.).
• Review freeze frame data: note engine RPM, engine load, temperature, and whether the fault occurred at a specific RPM or temperature range.

Inspect for obvious mechanical causes

• Open the hood and check for oil leaks around the cam covers and CPS area.
• Look for signs of oil or coolant intrusion near the CPS connector or routing.
• Visually inspect the camshaft timing cover area for signs of timing chain/belt wear, misalignment, or damage.

Check the Camshaft Position Sensor A (Bank 1)

• Locate CPS A on the Bank 1 side (per your engine code). Check the electrical connector for corrosion, dirt, broken pins, or loose fit.
• Disconnect, inspect, and reseat the connector. Apply dielectric grease if the terminals look clean but slightly stiff.
• If available, compare sensor resistance/signal with specifications from the service manual.

Inspect and test the wiring harness

• Inspect the wiring between CPS A and the PCM/ECU for cuts, abrasion, or heat damage. Look for chafed wires near moving parts or where harnesses pass near the engine.
• Verify continuity and resistance of the signal wire and ground wire with a multimeter. Check the 5V reference and ground at the sensor side (and at the PCM side if you have the right wiring diagram).
• Check for proper 5V reference supply to the CPS (and correct ground). A fluctuating or no reference can cause a false fault.

Test the cam sensor output and timing signal

• If you have an oscilloscope or a high-quality scan tool with live sensor data, observe the CPS A waveform while the engine cranks and during running.
• A healthy cam position sensor typically produces a stable waveform with a frequency that correlates with RPM. A flatline or highly erratic waveform indicates a bad sensor or wiring issue.
• Compare observed signal against the service manual’s expected waveform/specs for Bank 1.

Check the crank position sensor relationship

• Since cam/crank synchronization is critical, confirm crank sensor operation (P0335 or similar codes can accompany cam codes). If the crank sensor is faulty or its signal is intermittent, it can complicate cam sensor readings.
• Ensure crank sensor wiring is intact and the sensor is secure.

Evaluate timing hardware (if indicated)

• If timing marks are off or timing components show wear, you may need to verify timing chain/belt, tensioners, and guides. A retimed engine or worn timing parts can cause persistent cam sensor signal issues.
• For Subarus, timing components are a more extensive repair and often require professional service due to potential engine damage if done incorrectly.

Clear codes and test drive

• After performing the above checks and addressing any issues found (sensor, wiring, connectors, or timing), clear the codes with your scan tool.
• Take a test drive under various conditions (idle, light throttle, and higher RPM) to see if P0345 returns. If it does, proceed with replacement of the CPS or more extensive diagnostics as needed.

When to replace the Camshaft Position Sensor A (Bank 1)

• Replaces are warranted if the sensor is physically damaged, exhibits inconsistent electrical output, or when oscilloscope/data logger shows the sensor signal is out of spec despite wiring tests.
• If wiring and connectors test good but the problem persists, sensor replacement is typically the next logical step.

When to involve a professional

• If you lack diagnostic tools (scope or graphing capability) or if timing chain/belt and tensioner service is required, a professional mechanic is advised.
• If the issue is intermittent or involves multiple subsystems (engine timing, ignition, and fuel) a professional diagnostic may save misdiagnosis time and reduce risk of further damage.

RELATED CODES

• P0340 Camshaft Position Sensor Circuit Malfunction (Bank 1)
• P0341 Camshaft Position Sensor Range/Performance (Bank 1)
• P0345 Camshaft Position Sensor A Circuit Bank 1 (the subject code)
• P0335 Crankshaft Position Sensor A Circuit (often related, as crank/cam timing are interdependent)
• P0346-P0349 (Camshaft Position Sensor Circuit variations for other banks or sensor A/B in some engines; may not apply identically to all Subaru engines)

REPAIR OPTIONS AND COSTS (2025 PRICES)

Notes:

• Prices vary by region, shop, and whether the part is OEM or aftermarket.
• Labor times assume a typical repair shop environment; actual labor rates may differ.

A. Camshaft Position Sensor A (Bank 1) replacement

• Parts: $40–$120
• Labor: $60–$180
• Typical total: $100–$300
• What this covers: New camshaft position sensor, basic reinstall, and code clearance.

B. Wiring harness or connector repair/replacement

• Parts: $10–$80 (connector or wiring portion)
• Labor: $60–$150
• Typical total: $70–$230
• What this covers: Repair or replacement of damaged CPS wiring or connector, reseating, and corrosion treatment.

C. Cam timing hardware inspection/adjustment (timing chain, tensioner, guides)

• Parts: $200–$600 (timing chain kit or tensioner kit if needed)
• Labor: $600–$1,200
• Typical total: $800–$1,800
• When applicable: If timing misalignment or wear is found to cause the cam sensor signal out of spec or if you observe timing marks out of spec during inspection.
• Caution: This is a major engine service; incorrect timing work can cause severe engine damage.

D. Crankshaft position sensor issues or related sensor work (if diagnosed)

• Parts: $40–$100 (for crank sensor) depending on vehicle
• Labor: $60–$180
• Typical total: $100–$280
• Note: If a separate crank sensor issue is also found, costs will add up.

E. Ignition, fuel system, or plug/coil work if misfire is present

• Spark plugs: $8–$20 each; coils: $40–$120 each
• Labor: $60–$150 (per component replacement)
• Typical total: $100–$500 depending on what’s replaced
• Reason: Misfire can accompany P0345; addressing misfires can be part of the broader repair plan.

F. ECU/PCM reprogramming or software updates

• Parts: Usually none (software update by dealer)
• Labor: $50–$150
• Typical total: $50–$150
• When applicable: If a known software/ECU issue is contributing to the symptom (rare).

DIY vs PROFESSIONAL

• DIY-friendly options:
  • Replacing the Camshaft Position Sensor A (Bank 1) and cleaning/reconnecting the CPS connector is within many DIY capabilities if you have basic tools and a torque spec.
  • Inspecting wiring harness and connectors for obvious damage and performing continuity checks with a multimeter.
  • Clearing codes and test-driving to verify results.
• DIY caveats:
  • Confirm exact sensor location from your engine code and service manual; bank mapping can differ.
  • If timing chain components are suspected or you lack the necessary tools, avoid attempting timing work yourself.
  • Resetting adaptive or learned values after sensor changes may be required; some vehicles need a relearn procedure.
• Professional path:
  • When timing components are suspected or when wiring harness faults are extensive.
  • If intermittent sensor readings with scope testing remain unresolved.
  • If you lack access to necessary diagnostic tools (oscilloscope, live data graphs).

PREVENTION

• Use quality sensors and connectors (prefer OEM or reputable equivalents) to reduce premature failure.
• Address oil leaks promptly; oil contamination around the CPS can cause erratic readings.
• Keep the CPS wiring routed away from hot exhaust components and moving parts; secure harnesses with proper clips to prevent chafing.
• Regularly inspect the engine bay for signs of moisture intrusion around the CPS connector (especially in humid climates or under shaking conditions).
• Maintain a healthy electrical system: clean battery terminals, ensure proper charging voltage, and fix electrical load issues as needed.
• If you notice repeated misfires or irregular idle, investigate fuel delivery and ignition components as part of a broader preventive approach.

DATA LIMITATIONS AND NOTE

• Data provided: No NHTSA owner complaints for this make/model/year/issue combination; No recalls found in NHTSA database.
• This guide uses general automotive knowledge and Subaru-specific considerations to outline diagnostic steps and repair options. Always confirm details with the official service manual for your exact engine code and configuration, as bank numbering and sensor placement can vary between FA20/FB20 variants and model years.
• If you have access to a Subaru service bulletin (TSB) or software update for your specific Year/Engine Code, consider that information as a supplement to the steps above. The provided data indicates no recalls; it does not preclude the existence of non-recall TSBs or dealer advisories.