P0340 on 2005-2009 Lexus LS: Camshaft Sensor Causes & Fixes

What's Unique About the 2005-2009 Lexus LS

The 2005-2009 Lexus LS spans two distinct generations: the LS 430 (2005-2006) with the 3UZ-FE engine and the LS 460 (2007-2009) with the 1UR-FSE engine. While the code's meaning is the same, the specific sensor locations and related components differ. A key issue, documented in a Technical Service Bulletin (L-TT-0007-10), is that low battery voltage can trigger a P0340 code, making a battery and charging system test a crucial first step before replacing parts. On the LS 430, the sensor is located near the front of the driver's side cylinder head, accessible after removing the timing belt cover. On the LS 460, which uses a timing chain, there are four camshaft sensors (intake and exhaust for each bank), and P0340 specifically refers to the intake sensor on Bank 1.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: Yes, this range covers two generations. The 2005-2006 models are the end of the 3rd generation (XF30) LS 430, which uses a timing belt. The 2007-2009 models are the beginning of the 4th generation (XF40) LS 460, which uses a timing chain. While the primary causes are similar, diagnostics related to timing components would be different. For example, a P0340 on an LS 430 could be caused by a frayed timing belt fragment interfering with the sensor, a scenario not applicable to the LS 460.

Symptoms You May Notice

• Check Engine Light and/or Check VSC light is on
• Engine is hard to start or cranks for a long time but won't start
• Engine stalls, especially at idle or low speeds
• Rough or unstable idle, sometimes dropping to 350-400 RPM
• Noticeable loss of power and poor acceleration
• Engine misfires
🎬 Watch: Common symptoms of a bad camshaft position sensor

Most Likely Causes

1. Failing Camshaft Position Sensor 🔴 High Probability → Shop Engine Camshaft Position Sensor Sensors are electronic components that operate in a high-heat environment and can fail from age and heat cycles. They are a common wear item.
   How to confirm: After confirming battery voltage is good, the most common fix is replacing the sensor. You can also test the sensor's resistance with a multimeter 🎬 Watch: How to test a camshaft position sensor or swap it with the Bank 2 sensor (if identical, primarily on LS 460) to see if the code follows to P0345.
   Typical fix: Replace the Bank 1 (driver's side) intake camshaft position sensor.
   Est. part cost: $70-$150
2. Low Battery Voltage or Failing Alternator 🟡 Medium Probability → Shop Vehicle Battery A Lexus Technical Service Bulletin (L-TT-0007-10) explicitly states that low battery voltage can cause code P0340 due to inconsistent engine cranking speed. Forum users on ClubLexus have confirmed that a weak battery can trigger a cluster of codes including P0340, P0335, and VSC warnings, which are resolved with a new battery.
   How to confirm: Test the battery voltage with the car off (should be ~12.6V) and while running (should be ~13.5-14.5V). A load test at an auto parts store is the most definitive way to confirm battery health.
   Typical fix: Charge or replace the battery. If the charging voltage is low, the alternator needs to be tested and likely replaced.
   Est. part cost: $150-$300 for a battery, $300-$600+ for an alternator.
3. Damaged Wiring or Connector ⚪ Low Probability Engine bay heat can make wiring insulation brittle over time, leading to cracks or breaks, especially near the connector. Rodent damage is also a possibility. On the LS 430, timing belt debris can also damage the sensor or its wiring.
   How to confirm: Visually inspect the wiring harness and connector for the Bank 1 camshaft sensor. Look for cracks, corrosion, loose pins, or chewed wires. Check for continuity with a multimeter from the sensor connector to the ECM.
   Typical fix: Repair the damaged section of the wiring harness or replace the connector pigtail.
   Est. part cost: $10-$50

Rare But Worth Checking

• Failing Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is very uncommon, but forum discussions mention that ECU failure can cause this code after all other possibilities are exhausted. On older Lexus models like the LS 400, leaking capacitors were a known issue, and while less common on the LS 430/460, a faulty ECM driver for the sensor circuit remains a remote possibility. A confirmed repair involved a loose pin at the ECU socket, which mimics an ECM or wiring fault.
• Timing Belt/Chain Issue: → Shop Engine Timing Chain If a timing belt (LS 430) jumps a tooth or a timing chain (LS 460) is excessively stretched, it can throw off the cam/crank correlation and trigger this code. This is rare and would usually be accompanied by other codes and more severe running issues like rattling noises on startup (LS 460) or physical damage to the sensor from a loose belt (LS 430).
• Damaged Reluctor Wheel: The sensor reads teeth on a reluctor wheel (or ring) on the camshaft. If this wheel is damaged, cracked, or has missing teeth, the sensor will generate an erratic signal. This is extremely rare and typically would only happen during major engine work or a catastrophic timing failure.

Diagnosis Steps

1. Read all codes with an OBD-II scanner. Note any other codes like P0335, P0345, or VSC warnings, as they often appear together with P0340 due to low voltage.
2. CRITICAL: Test the battery and charging system first. A weak battery is a known cause. Check voltage with the engine off (~12.6V) and running (~13.5-14.5V). Get a load test. Resolve any issues here before proceeding.
3. Locate the Bank 1 (driver's side) intake camshaft position sensor. On the LS 430, it's at the front of the cylinder head under the plastic timing cover. 🎬 See this LS 430 camshaft sensor replacement walkthrough On the LS 460, it's one of two sensors on the front of the driver's side cylinder head.
4. Visually inspect the sensor's connector and wiring for any signs of damage, corrosion, oil contamination, or loose connections. These connectors are known to become brittle with age.
5. If wiring looks good and the battery is healthy, the most common repair is to replace the Bank 1 camshaft position sensor with a quality OEM part (e.g., Denso).
6. For LS 460: As a diagnostic test, you can swap the Bank 1 intake sensor with the Bank 2 intake sensor. Clear the codes and see if the fault moves to P0345. If it does, the sensor is confirmed bad.
7. If the code returns after replacing the sensor, perform a continuity test on the wiring harness between the sensor connector and the ECM to rule out an open or shorted wire. Crucially, also check for a loose pin fit at the ECM connector itself, as this has been a confirmed fix.
8. For LS 430: Remove the timing belt cover and inspect for a frayed belt or debris that could be interfering with the sensor or reluctor wheel.
9. If all else fails, the issue could be a mechanical problem (timing jumped, damaged reluctor wheel) or, in very rare cases, a faulty ECM.

Parts You'll Likely Need

• Camshaft Position Sensor (Bank 1) (OEM #LS 430 (3UZ-FE): 90919-A5002 (replaces 90919-05036). LS 460 (1UR-FSE): 90919-05061 (Bank 1 Intake).) — This is the most frequent point of failure for the P0340 code after ruling out battery issues.
  Trusted brands: Denso, Aisin, Genuine Lexus
  OEM price range: $100-$150
  Aftermarket price range: $50-$90

Related Codes That Often Appear With This One

• P0335 — Crankshaft Position Sensor Circuit Malfunction. The TSB L-TT-0007-10 explicitly mentions that low battery voltage can cause both P0340 and P0335 to appear together.
• P0345 — Camshaft Position Sensor 'A' Circuit Bank 2. If the underlying cause is systemic, like low voltage or a major wiring issue, both bank sensors may report errors. This code will also appear if you swap the Bank 1 and Bank 2 sensors for diagnosis on an LS 460.
• Check VSC — The Vehicle Stability Control (VSC) system relies on proper engine data. When a critical engine sensor like the camshaft position sensor fails, the ECU will often disable the VSC system as a precaution, illuminating the VSC warning light.

Technical Service Bulletins (TSBs) & Recalls

• L-TT-0007-10: Notes that low battery voltage can contribute to a MIL "ON" condition for P0340 due to inconsistent engine cranking speed.

Platform-Specific Known Issues

• TSB L-TT-0007-10 confirms that low battery voltage is a specific cause for P0340 on this platform, which is not always the case for all vehicles.
• On the LS 430 (3UZ-FE), the sensor is located behind the timing belt cover, and a fraying timing belt can physically damage the sensor or its wiring.
• On the LS 460 (1UR-FSE), there are four camshaft sensors in total (intake and exhaust for each bank). P0340 specifically refers to the intake sensor on Bank 1 (driver's side). A Reddit user with a 2007 LS 460 reported getting P0340 along with P0345, P0365, and P0390, all pointing to a systemic electrical issue.

Mechanic-Grade Diagnostic Values

• LS 460 (1UR-FSE) Camshaft Position Sensor Voltage (DTC Trigger) — expected: Signal should be a rectangular waveform switching between approx. 1.0V and 4.0V.. Failure: DTC P0340 is set if the ECM sees voltage remain below 0.3V or above 4.7V for more than 5 seconds while the engine is revolving.
• LS 430 (3UZ-FE) Camshaft Position Sensor Resistance — expected: 835 - 1,400 Ohms (cold). 1,060 - 1,645 Ohms (hot).. Failure: A reading outside of this range indicates a faulty sensor coil.
• LS 460 (1UR-FSE) Sensor Connector Voltage Check (Key On, Engine Off) — expected: Using a multimeter, you should find one pin with 5V (reference), one with 0V (ground), and a third signal wire which may also show 5V or a different reference voltage depending on the test method.. Failure: Absence of the 5V reference or a bad ground points to a wiring or ECM issue, not a sensor failure.

Scan Tool Commands That Help

• Techstream: Read Freeze Frame Data — Crucial for understanding the engine's state (e.g., speed, temperature, load) at the exact moment the P0340 fault was triggered. This can help differentiate between a startup issue and a failure while running.

Wiring & Ground Locations

• LS 430 (3UZ-FE) ECM Pins — At the Engine Control Module (ECM).. The Bank 1 Camshaft Position Sensor wires terminate at pins E5-21 (G2) and E5-20 (G2-). This is essential for end-to-end continuity testing from the sensor to the ECM.
• LS 430 (3UZ-FE) Engine Ground Straps — There are main ground straps on the back of each cylinder head that connect to the firewall/chassis.. A poor engine ground can introduce electrical noise and voltage drops, potentially causing erratic sensor readings and triggering codes like P0340.
• LS 430 (3UZ-FE) Brittle Connectors — The plastic connectors for camshaft sensors, VVT solenoids, and injectors become extremely brittle from heat and age.. The connector housing can break during service (like a spark plug change), leading to a poor connection that triggers P0340. The fault is the connector, not the sensor. Replacement connector bodies are available.

Real Owner Repair Stories

• ScannerDanner Forum (Toyota Celsior with 3UZ-FE engine swap (equivalent to 2001-2006 Lexus LS430)) — P0340 (cam sensor) and P1350 (VVT sensor) codes, with intermittent crank-no-start.
  ❌ Tried (didn't work) Swapping sensors with known-good ones., Confirming continuity on all sensor wires from connector to ECU., Checking sensor resistance values., Swapping signal wires at the ECU to confirm the ECU could read the signal on a different pin.
  ✅ What actually fixed it A loose pin was found in the ECU socket. Pushing the pin back into place for a snug fit resolved the codes.
• ClubLexus Forum (2008 Lexus LS460, 200,000 miles) — No start, starter does not engage. Check VSC light on. Multiple codes stored: P0335, P0340, P0345, P0365, P0390.
  ❌ Tried (didn't work) Initial diagnosis pointed towards the cluster of cam/crank sensors due to the codes.
  ✅ What actually fixed it The owner took the car to the dealer, who diagnosed a bad starter motor. While the final outcome confirming the fix for all codes isn't posted, this story shows that a complete no-crank/no-start condition can present with a full suite of cam/crank codes, potentially misleading the diagnosis away from the starter circuit.

When the Usual Fixes Don't Work

• In a documented case involving a 3UZ-FE engine (LS430), replacing the camshaft position sensor for a P0340 code did not fix the issue. Further diagnosis revealed that all wiring had perfect continuity and resistance. The root cause was ultimately found to be a single loose pin in the main ECU connector socket. This highlights that even when a code directly implicates a component, the true fault can be a poor connection at the control module, which is often overlooked after a simple continuity test passes.

OEM Part Supersession History

• 90919-05060 → 90919-T5005 — Part update or manufacturer change.
  Heads up: Applies to some sensors on the LS460. Always verify the correct part number for the specific sensor location (e.g., intake/exhaust, bank 1/2) with a VIN.

Model Year Variations Within This Range

• 2001-2006 (LS430): The wiring harness connectors used on the 3UZ-FE engine differ between the early models with the 5-speed automatic (2001-2003) and the later models with the 6-speed automatic (2004-2006). Replacement connector part numbers must be sourced accordingly.