P0340 Code: Toyota Tacoma (2016-2023) - Causes, Symptoms & Fixes

1. CODE MEANING AND SEVERITY

• Code: P0340 – Camshaft Position Sensor A Circuit Malfunction (often labeled for Bank 1 on many engines; in V6 applications this relates to the camshaft position sensor circuit for the primary cam location used by the PCM to synchronize firing).
• What it means in plain terms: The engine computer is not seeing a normal, expected signal from the camshaft position sensor (CMP) or the signal is out of expected range. Without a proper CMP signal, the PCM cannot reliably time the ignition and/or fuel injection, which can lead to drivability issues.
• Severity on a 2016-2023 Toyota Tacoma: Moderate. The vehicle may run poorly, misfire, stall, or be difficult to start. In some cases it can run in limp/limited mode or fail to start. Because P0340 disrupts timing signals, it can significantly affect performance, fuel economy, and reliability until corrected.

Important data note

• NO recalls were found in the NHTSA database for this make/model/year/issue combination.
• No NHTSA owner complaints are listed for this issue in the provided data.

2. COMMON CAUSES ON TOYOTA TACOMA

• Faulty Camshaft Position Sensor (CMP) itself
  • Sensor failure or degraded internal wiring can produce a weak or intermittent signal.
• CMP wiring harness or connector problems
  • Corrosion, bent/pin damage, water intrusion, or loose connections can break or degrade the signal.
• Damaged or worn reluctor/target on the camshaft
  • A damaged reluctor ring or misalignment of the cam gear can distort or erase the CMP signal.
• Timing system issues that affect CMP signal reference
  • Timing chain/belt wear, tensioner/guide wear, or sprocket wear can cause timing to drift and CMP signal to fall out of sync with the crankshaft signal.
• Crankshaft Position Sensor (CKP) issues or misalignment
  • While P0340 targets CMP, simultaneous CKP faults or poor CKP/CMP correlation can trigger related symptoms or help mask CMP problems.
• Electrical/system voltage problems
  • Low battery voltage or poor grounding can produce weak sensor signals and false readings.
• PCM/ECU concerns (rare)
  • A faulty PCM could misinterpret or fail to process CMP input properly, though this is less common.

3. SYMPTOMS

• Check Engine Light (CEL) or MIL illuminated.
• Poor acceleration, hesitation, or reduced engine power.
• Rough idle or engine misfires.
• Intermittent stalling or failure to start.
• Degraded fuel economy.
• In some cases, the engine may run in a degraded mode (limp mode) to preserve drivability.

4. DIAGNOSTIC STEPS
   Note: Use a quality OBD-II scanner and, if possible, a lab scope or oscilloscope for CMP signal waveform analysis. Follow Toyota service data for exact procedures and torque specs.

• Step 1: Confirm and isolate

  • Retrieve DTCs with a scanner. Note any other related codes (e.g., P0335 for CKP, P0341/P0345 for CMP range/Bank variations, P0300 for multi-mpark misfire, etc.).
  • Check for vehicle symptoms and verify whether the issue is intermittent or persistent.

• Step 2: Inspect electrical connections

  • Inspect CMP sensor connector and wiring harness for corrosion, bent pins, or damaged insulation.
  • Disconnect and reconnect the CMP connector, ensuring a clean, solid connection.
  • Check for obvious wiring damage along the harness routing.

• Step 3: Test the CMP sensor circuit (electrical checks)

  • With the ignition off, back-probe the CMP harness to verify:
    • 5V reference voltage at the sensor signal circuit from the PCM (or specified reference).
    • Good ground continuity.
  • Check for voltage drop, shorts to ground or battery voltage, and continuity along the harness.
  • If available, use a scope to view the CMP output waveform. You should see a clean, repeating waveform synchronized with engine RPM. A missing waveform, irregular signal, or no signal indicates sensor or wiring failure.

• Step 4: Check for timing and mechanical issues

  • Inspect the camshaft timing system (timing chain/belt, tensioners, guides, sprockets) for wear or misalignment if the CMP signal appears compromised or if timing marks indicate drift.
  • If the engine has been recently rebuilt or there was a timing-related work, ensure the timing is set to the proper specification and that the sensor reference reluctor ring alignment is correct.

• Step 5: Check the CKP sensor and its circuit

  • Since CMP and CKP signals are used together, verify the CKP signal is present and stable. A missing/bad CKP can cause symptoms similar to CMP failure or mask CMP faults.
  • Resolve any CKP issues before assuming CMP is at fault.

• Step 6: Confirm voltage and ground integrity under load

  • A weak ground or fluctuating voltage can cause sporadic CMP readings. Check battery health, alternator output, and relevant grounds (engine block, PCM ground).

• Step 7: Replace CMP sensor if electrical/verification steps indicate fault

  • If CMP signal is missing or out of spec and wiring is sound, replace the CMP sensor with the correct Toyota part. Re-check and clear DTCs after installation.

• Step 8: Post-repair verification

  • Clear codes and perform a road test (watch for reappearance of P0340 or related codes).
  • Confirm CMP signal is clean and synchronous with CKP.
  • If needed, perform any PCM relearn or engine adaptivity procedures as per OEM tooling or service manual.

5. RELATED CODES

• P0341 – Camshaft Position Sensor A Circuit Range/Performance (Bank 1 or Bank 2 depending on engine variant)
• P0345 – Camshaft Position Sensor A Circuit Malfunction (Bank 2)
• P0335 – Crankshaft Position Sensor A Circuit
• P0336 – Crankshaft Position Sensor A Circuit Range/Performance
• P0300 – Random/Multiple Cylinder Misfire (often seen when CMP/CKP signaling is inconsistent)
  Note: On the Tacoma’s 3.5L V6 configuration, bank numbering can vary; diagnose using the vehicle’s service information to map the correct bank to the sensor.

6. REPAIR OPTIONS AND COSTS (2025 PRICES)
   Prices vary by region, shop, and required work. The ranges below are typical ballparks to help you budget.

• Camshaft Position Sensor (CMP) replacement only

  • Parts: approximately $25–$80
  • Labor: about 0.5–1.5 hours
  • Estimated total: roughly $130–$250
  • Notes: In most cases no timing work is required. After replacement, clear the code and perform a road test; some vehicles may require a short relearn or idle learn with a scan tool.

• CMP wiring/connector repair

  • Parts: minimal (connectors, wires)
  • Labor: 1–2 hours
  • Estimated total: $100–$350
  • Notes: If harness repair is feasible without full harness replacement, costs can stay modest. Avoiding a full harness replacement saves money.

• Timing system service (rarely required solely for P0340)

  • Parts: tensioners, guides, or timing chain/belt
  • Labor: 3–6 hours
  • Estimated total: $500–$1500
  • When it applies: if a worn timing chain, tensioner, or misalignment is contributing to incorrect CMP reference or if CMP signal is consistently unreliable due to mechanical timing drift.
  • Notes: This is a more invasive repair; confirm necessity with timing marks and service manual procedures.

• CMP sensor plus wiring harness replacement combo (if both fail)

  • Parts: CMP sensor + wiring harness portion
  • Labor: 1–3 hours
  • Estimated total: $150–$500
  • Notes: Combine replacements if multiple CMP-related faults are diagnosed.

• PCM/ECU-related fault (rare)

  • Parts: PCM replacement or reprogramming
  • Labor: 1–3 hours (plus programming)
  • Estimated total: $300–$1000
  • Notes: Only if diagnostics indicate PCM misbehavior and all sensor wiring checks out.

7. DIY VS PROFESSIONAL

• DIY-friendly scenarios (lower risk)
  • You have basic hand tools, a good workspace, and a reliable scanner/scope to verify CMP signal.
  • You are comfortable disconnecting electrical connectors, cleaning grounds, and replacing a small sensor with no timing work needed.
  • You can complete CMP sensor replacement quickly and test drive with a diagnostic scan afterward.
• When to go PROFESSIONAL
  • Suspected timing chain/belt wear or tensioner issues.
  • Weak or intermittent CMP signal with concurrent CKP issues.
  • Suspected wiring harness problems that require extensive diagnosis or harness replacement.
  • If the vehicle needs PCM relearn or if OEM tooling is required for proper calibration.
  • If you’re not confident in handling timing-related components (risk of severe engine damage if timing is set incorrectly).

Safety note: If you must rotate the engine at any point or remove the timing cover, follow the Toyota service manual precisely. Incorrect timing can cause severe engine damage.

8. PREVENTION

• Regular electrical maintenance
  • Inspect and clean CMP and CKP connectors, apply dielectric grease to protect pins from moisture and corrosion.
  • Inspect wiring harness routing for chafing or damage; repair promptly.
• Use quality parts
  • When replacing CMP sensors, use OEM or equivalent reputable parts to minimize early failures.
• Maintain the timing system
  • For interference engines, follow service intervals for timing chain/belt components, tensioners, and guides. Address unusual engine noises or rough running promptly to prevent timing-related issues.
• Electrical system health
  • Keep the battery in good condition; ensure proper starter/alternator performance and clean grounds to avoid voltage fluctuations that can affect sensor signals.
• Regular diagnostics
  • If you notice intermittent drivability issues, consider a periodic CMP/CKP signal check with a scope during a test drive to catch issues early.

Important data limitations

• The provided data shows no NHTSA owner complaints for this issue and no recalls for this model/year combination. No recalls found in NHTSA database.
• All guidance above combines standard diagnostic practice for P0340 with Toyota Tacoma specifics. Always refer to the official Toyota service information for your exact model year and engine variant for wiring diagrams, sensor part numbers, torque specs, and procedure sequences.
• If in doubt, consult a qualified technician to avoid potential engine damage or mis-timed operation.