P0335 Code: Subaru Forester (2019-2024) - Causes, Symptoms & Fixes

Comprehensive diagnostic guide for OBD2 code P0335 on 2019-2024 Subaru Forester

Data note based on the provided NHTSA data:

• No owner complaints found for this make/model/year/issue combination.
• No recalls found in the NHTSA database.
• The guide below relies on general automotive knowledge for CKP (Crankshaft Position Sensor) diagnostics and Subaru-specific common patterns, plus the code meaning. Data limitations mean this should be treated as a practical guide, not a definitive official bulletin.

CODE MEANING AND SEVERITY

• What the code means:
  • P0335 = Crankshaft Position Sensor "A" Circuit. It indicates a fault in the primary crankshaft position sensor circuit—this sensor provides the engine control module (ECM) with a reference signal of crank angle and speed, which is essential for ignition timing and sequential fuel injection.
  • On many 4-cylinder Subarus (including Forester engines used in 2019–2024 models), this is the primary CKP circuit. The “A” designation typically refers to the main CKP sensor circuit; some engines may have a secondary/backup circuit labeled “B,” but P0335 is the common CKP circuit fault.
• Severity and potential impact:
  • High-severity powertrain fault. The engine may fail to start, stall, or run in a degraded mode. In many cases, a stored P0335 will be accompanied by a no-start condition or a hard stall, potentially leaving you stranded.
  • If the vehicle starts and runs, you may experience intermittent stalling, hesitation, reduced power, misfires, or irregular idle.
  • Prolonged driving with a confirmed CKP circuit fault can lead to catalytic converter overheating or engine damage in rare cases if timing and fuel operation become inconsistent.
• Data context:
  • No recalls or official complaints are reported in the provided data for this specific make/model/year/issue. This does not rule out typical CKP failures; it only reflects the data you supplied.

COMMON CAUSES ON SUBARU FORESTER

• Faulty crankshaft position sensor (CKP) itself.
• Damaged, corroded, loose, or pinched CKP sensor wiring or connector (harness to sensor) (including insulation breakdown near hot engine surfaces or where the harness passes near moving parts).
• Oil or coolant contamination around the CKP sensor or its reluctor/tone ring, often from leaks or gasket failures.
• Damaged reluctor ring (tone wheel) on the crankshaft or misalignment of the reluctor relative to the sensor.
• Wiring harness chafing or missing shielding due to engine movement or wear (can create intermittents or open circuits).
• Grounding issues or poor 5V reference supply to the CKP circuit (ECM reference or ground circuit faults).
• ECM (engine control module) fault or voltage reference irregularities (less common but possible).
• Aftermarket accessories or wiring changes that affect the CKP circuit or introduce noise.
• In some cases, severe engine timing issues (rare for CKP-only faults) can produce CKP circuit faults, especially if the crankshaft position is repeatedly out of range or the tone ring is compromised.
• Note: In Foresters, engine options include 2.5L four-cylinders in many trims; CKP behavior is similar across these engines, but exact sensor location and connector color may vary slightly by year and submodel.

SYMPTOMS OF P0335 ON A 2019–2024 FORESTER

• Engine does not start or cranks but fails to start.
• Engine starts inconsistently or stalls while idling or during acceleration.
• Check Engine Light (CEL) is on with code P0335 stored.
• Misfires, rough idle, and reduced engine power when the CEL is on.
• Possibly no tachometer signal or erratic tachometer behavior (since CKP drives ignition timing).
• Intermittent no-start or stall situations, sometimes related to engine temperature or vibration.

DIAGNOSTIC STEPS

Note: Always follow basic safety procedures. If you’re not comfortable with electrical testing or if the engine is hot, pause and consider professional help.

Step 1 — Confirm the problem and related codes

• Use a scan tool to confirm P0335 is present and to see if any related codes (P0336, P0337, P0338, P0339, P0340, etc.) are stored.
• Check freeze-frame data for engine RPM, engine load, and other parameters at the time the code was set.

Step 2 — Check battery and charging system

• Ensure battery voltage is solid (12.6V or higher when off; about 13.5–14.8V when running).
• A weak battery or alternator issue can cause spurious sensor readings or voltage drops that trigger codes like P0335.

Step 3 — Visual inspection of CKP sensor and harness

• Locate the CKP sensor (location varies with engine type; typically near the crankshaft pulley/timing area or a bolt-on sensor in the timing cover area).
• Inspect the connector and wiring for cracked insulation, corrosion, bent pins, or loose connections.
• Check for oil leaks that could contaminate the sensor or the wiring.
• Look for signs of heat exposure or chafed wires against the engine block, exhaust components, or belts.

Step 4 — Inspect the reluctor ring and sensor alignment

• If accessible, inspect the crankshaft reluctor/tone wheel for missing teeth, damage, or debris.
• Verify sensor mounting distance and alignment per service manual (some sensors are sensitive to misalignment or improper gap).

Step 5 — Electrical tests on the CKP circuit

• With ignition off, disconnect the CKP sensor and inspect the connector pins for corrosion.
• Test the sensor circuit continuity to the ECM using a multimeter:
  • Check the 5V reference circuit, ground, and signal (as applicable to your engine's CKP wiring diagram).
  • Compare measured values to the vehicle’s service manual specifications.
• Inspect for a stable 5V reference and good ground when the ignition is turned on. A bad reference or ground can cause a false P0335 reading.

Step 6 — Check sensor resistance and signal validity (tech level)

• If you have access to an oscilloscope or a graphing multi-meter, monitor the CKP sensor signal while cranking. You should see a clean, repeating waveform that corresponds to crank speed.
• If there is no signal or an erratic signal, the CKP sensor or its wiring is suspect.

Step 7 — Rule-out mechanical and timing issues

• If the engine has timing components (timing chain, tensioner) that are failing, it could affect CKP readings or generic timing events and trigger related codes. This is less common for CKP-only faults but should be considered if mechanical timing work is suspected.

Step 8 — Test with an alternate power/ground path (advanced)

• If the shop has the capability, verify the CKP circuit by temporarily probing with a known-good harness or wiring path to see if the signal reappears. This is typically done by trained technicians.

Step 9 — Decide on repair path

• If the CKP sensor and wiring test fail consistently, plan to replace the CKP sensor and/or repair the harness.
• If wiring damage is extensive, consider harness replacement or repair by a professional.
• If all CKP-related checks pass and the problem persists, consider ECM fault or a rare, related sensor misalignment; professional diagnosis is recommended.

RELATED CODES

• P0330 Knock sensor related codes are not directly tied to CKP, but some vehicles may store other engine sensor codes alongside P0335. More relevant CKP-related codes include:
  • P0336 Crankshaft Position Sensor "A" Circuit Range/Performance
  • P0337 Crankshaft Position Sensor "A" Circuit No Signal
  • P0338 Crankshaft Position Sensor "A" Circuit Intermittent
  • P0339 Crankshaft Position Sensor "A" Circuit No Signal (possible variant)
• If you see P0330–P0339 together, focus first on the CKP circuit integrity and wiring, then check related sensors if symptoms persist.

REPAIR OPTIONS AND COSTS (2025 prices)

Note: Prices are rough industry ranges and can vary by region, shop, part quality (OE vs aftermarket), and vehicle trim.

• Crankshaft Position Sensor replacement (CKP sensor only)
  • Parts: typically $25–$120 (OEM vs aftermarket; higher for OEM).
  • Labor: about 0.5–1.5 hours depending on accessibility.
  • Estimated total: $100–$350 (often around $150–$300 at a typical shop).
• CKP sensor wiring/connector repair
  • Parts: minimal (connectors, pigtails if needed) in the $5–$40 range.
  • Labor: 1–2 hours if harness has to be repaired or replaced.
  • Estimated total: $150–$500 depending on damage and whether the harness can be repaired or must be replaced.
• CKP sensor plus harness replacement (if wiring is visibly damaged)
  • Parts: CKP sensor + harness segment or full harness repair kit.
  • Labor: 1–3 hours.
  • Estimated total: $250–$600.
• ECM (engine control module) fault or replacement
  • Parts: ECM replacement typically $400–$1,000 (or more for dealer units).
  • Labor: 1–3 hours.
  • Estimated total: $600–$2,000 (or higher if dealer programming is required).
• Timing components issue (rare for CKP-only code, but if suspected)
  • Parts: timing chain/brequency components, tensioners, guides.
  • Labor: 3–6+ hours depending on engine design.
  • Estimated total: $1,200–$4,000+.
• Leak-related or oil contamination contributing to CKP failure
  • Parts: oil seal/gasket repairs as needed (often $50–$300 for parts; labor scalable with scope).
  • Estimated total: $150–$800 depending on the extent.
• DIY costs (if you do it yourself)
  • CKP sensor: $25–$120 for parts.
  • Tooling: basic hand tools; if you don’t already own them, minor investment.
  • Net DIY cost: roughly $30–$150 (plus your time).

Important notes:

• These are typical ranges; actual prices will vary by dealership vs independent shop, region, and whether you use OEM Subaru parts or aftermarket equivalents.
• In some Forester configurations, the CKP sensor is somewhat access-limited; labor time can swing based on engine variant and transmission type.
• If the CKP issue is intermittent, expect to pay more for thorough testing and possibly multiple visits.

DIY vs PROFESSIONAL

• DIY considerations:
  • Suitable if you have basic mechanical skills, a good set of hand tools, a decent multimeter, and preferably a service manual or clear schematic for your engine variant.
  • Pros: lower cost, quick turnaround for simple sensor replacement.
  • Cons: risk of misdiagnosis, poor harness repair, or damage to sensitive connectors; some CKP sensors sit in a tight, hot, or hard-to-reach area.
• Professional considerations:
  • Pros: proper diagnosis with live data, oscilloscope testing if needed, correct replacement, proper torque specs, and reprogramming if required.
  • Cons: higher cost; potentially longer turnaround depending on shop backlog.

DIY steps you might perform (high level):

• Gather: CKP sensor replacement part, basic hand tools, dielectric grease, contact cleaner.
• Disconnect battery ground.
• Locate CKP sensor and inspect wiring/connectors for damage.
• If replacing sensor, unplug connector, release any clips, remove sensor, and install new sensor to the specified torque (check service manual).
• Reconnect harness, apply appropriate dielectric grease to connector, and ensure a clean, dry connection.
• Clear any codes with scan tool; test by starting the engine and verifying no P0335 returns.
• If the code returns or the problem persists, seek professional help.

PREVENTION

• Regularly inspect the CKP sensor and wiring during routine maintenance, especially if you notice oil leaks around the timing cover or crank area.
• Fix oil leaks promptly to prevent sensor contamination.
• Keep harness connectors clean; use dielectric grease on connectors that are exposed to engine heat and vibration.
• Ensure battery and charging system are healthy; voltage dips can trigger misreads in CKP circuits.
• Avoid excessive aftermarket electrical interference (e.g., after-market alarms, poorly shielded wiring) near the CKP area.
• If you notice stalling, rough idle, or a no-start condition, address the issue promptly; leaving CKP problems unfixed can lead to further engine operation issues or catalytic heating.

Summary

• P0335 on a 2019–2024 Subaru Forester indicates a fault in the Crankshaft Position Sensor A Circuit. It often presents as no-start, stalling, rough idle, or intermittent loss of power.
• Common causes include a faulty CKP sensor, damaged wiring or connectors, oil contamination, or a damaged reluctor/tone ring.
• Diagnostic steps focus on verifying sensor function, wiring integrity, power/ground references, and signal waveform during cranking.
• Related codes to review include P0336–P0339 (CKP circuit range, no-signal, or intermittent variants) and P0330 (less common for CKP but related to other sensor timing signals).
• Repair options range from sensor replacement and harness repair to, in rare cases, ECM or timing component work. Estimated costs for 2025 typically span from roughly $100–$350 for a straightforward CKP sensor replacement, up to several hundred dollars more if wiring or more extensive mechanical work is required.
• DIY replacement is often feasible for a competent amateur with the right manuals and tools; otherwise, professional diagnosis and repair are recommended to minimize risk and ensure proper test coverage.
• Prevention centers on keeping the electrical system clean and dry, fixing leaks promptly, and avoiding stress on the CKP wiring through regular inspection.