Camshaft Position Sensor “A” Circuit Bank 1 or Single Sensor

What P0340 means

The camshaft position sensor (called the VVT sensor on Toyota engines) reads a toothed rotor attached to the camshaft timing gear to tell the ECM the exact angular position of the camshaft relative to the crankshaft. Toyota's 1GR-FE uses a Magnetic Resistance Element (MRE) design on the intake camshaft timing gear — a 3-tooth trigger plate generates 3 pulses per camshaft revolution. The ECM uses this data alongside the crankshaft NE signal to assign fuel injection to the correct cylinder and to control variable valve timing (VVT) oil control solenoid operation. P0340 is stored on Bank 1 when no VVT sensor pulses are received while the engine is cranking, or when pulses disappear at an engine speed of 600 RPM or more during running. A two-trip detection logic applies to the cranking variant; a one-trip detection triggers P0340 during a running condition.

Symptoms

• Check engine light on
• Hard starting or extended cranking required before the engine fires — the ECM cannot identify the injection sequence without cam position data
• Rough, unstable idle immediately after start in some cases as the ECM falls back on crankshaft-only timing
• Loss of VVT (variable valve timing) function, which may produce flat power delivery and reduced fuel economy
• In severe cases, engine may not start at all — particularly if the CKP signal is also absent

Common causes

• Failed camshaft position sensor (CMP) — the MRE or Hall-effect element has failed internally
• Corroded or damaged connector at the CMP sensor — the sensor's two-pin or three-pin connector is vulnerable to water intrusion and oil contamination
• Open or shorted wiring in the VVT sensor signal circuit between the sensor and the ECM
• Timing chain jumped or stretched — if the chain has slipped, the cam and crank signals no longer align, and the ECM may interpret the misalignment as a cam signal fault
• Damaged camshaft timing gear assembly — the 3-tooth trigger plate on the cam gear is physically damaged or the gear has slipped on the shaft
• ECM VVT input circuit failure — rare, but possible if the sensor signal wire shorted to power at some point

Severity & driving advice

Severity: High — Can cause hard no-start, loss of VVT, and rough running. A jumped timing chain cause is serious and requires immediate engine-off diagnosis.

Can I drive? No-start if hard fault. If running, diagnose promptly.

Diagnostic approach

1. Check for companion CKP codes and note whether the engine starts — Factory data shows that if both P0340 and P0335 are stored together, the ECM may not have enough positional data to start — focus on restoring communication from both sensors before testing individually. If P0340 alone is stored and the engine runs, the cam signal is intermittent. Note that the ECM cross-checks cam and crank signals; if the engine cranks normally but P0340 is logged, the fault is in the cam sensor circuit specifically.
2. Inspect the sensor connector and wiring — Locate the Bank 1 VVT sensor (typically on the intake cam on Toyota V6 engines — there are two VVT sensors on 1GR-FE, one for each bank). Disconnect the connector and look for green corrosion, bent or backed-out pins, or oil contamination. Check that the connector seal is intact. Resistance in the signal wire between the sensor connector pin and the corresponding ECM pin should measure under 1 Ω; resistance to chassis ground should be 10 kΩ or higher.
3. Test the VVT sensor output signal — With the sensor connected and a back-probe or breakout box, crank or run the engine and observe the VV1 (Bank 1) signal switching. On an MRE-type sensor, the output is a digital on/off signal with each cam tooth. A lab scope should show three clean pulses per cam revolution. No pulses, or a flat line at supply voltage, confirms the sensor has failed. Verify 5V reference supply is present at the sensor before condemning the sensor itself.
4. Inspect the cam timing gear and chain if the sensor tests good — Factory procedure specifically calls for verifying valve timing if the cam sensor and wiring pass all checks. A stretched timing chain or a gear that has slipped on the camshaft produces a mis-phased cam signal. Compare the cam-to-crank angle using a scan tool that displays VVT target and actual angles, or verify timing marks with the engine at TDC. A jumped chain will also typically set a P0016 timing correlation code alongside P0340.

Make & model notes

Toyota: The 1GR-FE V6 (FJ Cruiser, 4Runner, GX460, Tacoma V6) has two VVT sensors — Bank 1 (VV1) and Bank 2 (VV2). P0340 is the Bank 1 (front-facing on RWD applications) sensor. Toyota uses a 3-tooth plate; a scan tool reading shows VVT actual angle. If the sensor is fine but angle is wrong, check the timing chain and VVT actuator for sludge — 5W-30 oil at the correct change interval prevents most VVT-related faults.

Dodge / Chrysler: The 3.6L Pentastar V6 uses independent cam sensors for each bank. P0340 on Pentastar is frequently caused by the sensor wiring chafing against the valve cover or ignition coil harness bracket. Inspect the routing of the Bank 1 cam sensor harness for wear points before replacing the sensor.

Ford: Ford's 4.6L and 5.4L 3-valve engines use a VCT (variable cam timing) system; P0340 on these engines can be caused by engine sludge blocking the VCT phaser oil passages, which prevents the cam from reaching its target position. An engine flush and oil change sometimes restores operation on lightly sludged engines.

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