P0340 on 2013 Scion FR-S: Camshaft Position Sensor 'A' Circuit Malfunction

What's Unique About the 2013-2013 Scion FR-S

For the 2013 Scion FR-S and its identical twin, the Subaru BRZ, the P0340 code is uniquely tied to a known manufacturing issue affecting early production models. The Subaru-designed FA20 boxer engine uses four cam sensors, and Technical Service Bulletins (TSBs) were issued because many 2013 vehicles set this code not due to a failed sensor, but because the physical air gap between the sensor and the camshaft reluctor wheel was out of specification. This makes it crucial for owners to investigate Scion TSB S-SB-0013-14 or Subaru TSB 11-130-13 before simply replacing parts, as the correct fix is often to measure the gap and install a specific shim to achieve the proper clearance of 1.25mm to 1.35mm.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Engine is difficult to start, has extended crank times, or cranks but won't start
• Engine stalls, hesitates, or runs rough, especially at idle
• Noticeable loss of power and acceleration
• Reduced fuel economy
• Engine may enter 'limp mode'

Most Likely Causes

1. Incorrect Camshaft Position Sensor Clearance 🔴 High Probability → Shop Engine Camshaft Position Sensor This is a well-documented issue for 2013 model year vehicles produced before VIN JF1ZNAA1#D#721474, as detailed in Scion TSB S-SB-0013-14. Early production models were built with clearances outside the target specification, causing the sensor to send an erratic signal.
   How to confirm: Follow the TSB procedure. This involves removing the sensor, using a digital caliper with a depth attachment to measure the depth from the mounting surface to the camshaft reluctor plate, and comparing it to the sensor's length to calculate the air gap. The target clearance is 1.25mm - 1.35mm.
   Typical fix: Install a single, specific thickness shim between the sensor and the timing cover as specified by the TSB to bring the clearance into the correct range. Do NOT stack shims. The TSB provides a chart to select the correct shim based on the measured clearance.
   Est. part cost: $10-$30 for a single shim or a kit.
2. Failed Camshaft Position Sensor 🟡 Medium Probability → Shop Engine Camshaft Position Sensor
   How to confirm: After confirming clearance is correct, test the sensor. A common DIY method is to swap the Bank 1 intake sensor (passenger side, top) with the Bank 2 intake sensor (driver side, top) and see if the code changes to P0345, which would indicate the sensor is faulty. A multimeter can also be used to check for proper resistance 🎬 See this guide on testing sensors with a multimeter between the sensor's terminals, which should be 1,630 to 2,740 Ω when cold.
   Typical fix: Replace the faulty camshaft position sensor. P0340 refers to the Bank 1 🎬 Watch: How to test and replace the Bank 1 sensor (passenger side) intake sensor. It is recommended to apply fresh engine oil to the new sensor's O-ring before installation.
   Est. part cost: $90-$130 for an OEM sensor.
3. Wiring or Connector Issue ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness and connector for the Bank 1 intake cam sensor for any signs of fraying, melting, corrosion, or loose pins. Use a multimeter to check for 5V reference voltage, ground, and signal continuity back to the ECM.
   Typical fix: Repair the damaged wire or clean/replace the connector.
   Est. part cost: $5-$50

Rare But Worth Checking

• Stretched Timing Chain or Failed Tensioner: → Shop Engine Timing Chain While less common, excessive slack in the timing chain can cause the camshaft and crankshaft positions to be out of sync, triggering this code. This would typically be accompanied by a rattling noise from the front of the engine, especially on startup.
• 2013 Model Year Valve Spring Recall: The 2013 FR-S and BRZ were subject to a major safety recall for engine valve springs that could fracture. While this is a separate mechanical failure, it can cause symptoms like rough idling and engine stalling that could be confused with a cam sensor issue. It is critical to verify if the recall work has been performed on any 2013 model, as some owners reported engine issues after the recall was performed, sometimes due to technician error during the complex repair.
• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is a very rare cause. The ECM should only be considered after all other possibilities, including sensors, wiring, clearance, and mechanical timing, have been thoroughly ruled out.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0340 is present and check for any other related codes.
2. Research Technical Service Bulletins (TSBs). For a 2013 FR-S, TSB S-SB-0013-14 is highly relevant and should be the first point of investigation. Note the affected VIN range.
🎬 Watch this walkthrough on fixing the P0340 code
3. Locate the Bank 1 (passenger side) intake camshaft position sensor. It is the upper sensor on the front timing cover on the right side of the engine.
4. Inspect the sensor's wiring and connector for any visible damage, corrosion, or loose pins.
5. Following the TSB procedure, remove the sensor (one 10mm bolt) and measure the camshaft position sensor clearance using a digital caliper. The target is 1.25mm - 1.35mm.
6. If the clearance is out of spec, consult the TSB chart to select the single correct shim needed to achieve the target gap. Order and install the shim.
7. If the clearance is within spec, test the sensor itself. The easiest method is to swap it with the Bank 2 (driver's side) intake sensor. Clear codes and see if a P0345 code appears. If it does, the original sensor is bad.
8. If the sensor is confirmed faulty, replace it with a new, quality part. Apply a little fresh engine oil to the new sensor's O-ring before installation.
9. If the sensor, wiring, and clearance are all good, consider less common causes like timing chain stretch (listen for rattling) or a potential ECM issue.
10. Clear the trouble codes from the ECM memory and perform a test drive, including varied RPMs, to confirm the repair is successful and the Check Engine Light does not return.

Parts You'll Likely Need

• Camshaft Position Sensor Shim (OEM #SU003-04600 (Shim Kit)) — This is the most likely fix for a 2013 model due to the known TSB regarding incorrect sensor clearance. The TSB lists individual shim part numbers based on thickness needed (e.g., 10130AA130 for 0.2mm, 10130AA120 for 0.3mm, etc.).
  Trusted brands: Subaru, Toyota
  OEM price range: $10-$30
• Camshaft Position Sensor (OEM #SU003-00414) — If the sensor itself has failed after clearance has been verified, it will need to be replaced. This is the second most common cause. The equivalent Subaru part number is 22056AA140.
  Trusted brands: Denso, Mitsubishi Electric, NGK
  OEM price range: $90-$126
  Aftermarket price range: $40-$105
• Camshaft Sensor O-Ring (OEM #SU003-00185) — The O-ring should be replaced whenever the sensor is removed to prevent oil leaks. It is a one-time use item.
  Trusted brands: Subaru, Toyota
  OEM price range: $3-$8

Related Codes That Often Appear With This One

• P0341 — This code indicates a range/performance problem with the same Bank 1 intake sensor circuit, often appearing alongside P0340 as they both relate to signal quality from the same sensor.
• P0301, P0302, P0303, P0304 — These are misfire codes for cylinders 1-4. A faulty camshaft position sensor signal disrupts ignition and fuel timing, leading to misfires. The TSBs for the FR-S explicitly list these codes as potential companions to P0340 caused by the clearance issue.
• P0345, P0346, P0365, P0366, P0390, P0391 — These are codes for the other three camshaft position sensors on the engine (Bank 2 Intake, Bank 1 Exhaust, Bank 2 Exhaust). The TSBs group all these codes together as being potentially caused by the same sensor clearance issue at their respective locations.

Technical Service Bulletins (TSBs) & Recalls

• S-SB-0013-14: Supersedes the earlier TSB. Details the procedure for inspecting camshaft position sensor clearance and installing a shim to correct DTCs P0340, P0341, P0345, etc., on 2013 FR-S vehicles built before VIN JF1ZNAA1#D#721474.
• S-SB-0033-13 Rev: An earlier version of the TSB that also identified incorrect camshaft position sensor clearance as the cause for P0340 and related codes.
• Subaru TSB 11-130-13R: The equivalent bulletin for the Subaru BRZ, covering the same FA20 engine issue and repair procedure.

Platform-Specific Known Issues

• TSB S-SB-0013-14 / S-SB-0033-13 Rev: These TSBs are the definitive guide for this issue on 2013 models. They identify incorrect camshaft position sensor clearance from the factory as the root cause for P0340 and a host of other cam and misfire codes. The fix involves precise measurement and adding a specific shim, not just replacing the sensor.
• Owner Experience: The Shim Fix Works: In a thread on ft86club.com, multiple users with 2013 models confirm that having the dealer perform the TSB by measuring and shimming the sensor permanently resolved their P0340/P0341 codes after failed attempts to just replace the sensor.
• Owner Experience: Misdiagnosis is Common: One user on ft86club.com reported their dealer had the car for a month, attempting the shim fix twice and even replacing a fuel injector, but the code kept returning, highlighting how even dealers can struggle if the TSB procedure isn't followed perfectly or if another issue is present.

Mechanic-Grade Diagnostic Values

• Camshaft Position Sensor Internal Resistance — expected: 1,630 to 2,740 Ω (cold) or 2,065 to 3,225 Ω (hot). Failure: A reading outside of this range, or an open/short circuit, indicates a faulty sensor.
• Sensor Connector Voltage (Key On, Engine Off) — expected: Pin 1 (Power Supply from ECM) to Ground: ~5V. Pin 2 (Signal) to Ground: ~5V. Pin 3 (Ground) to Ground: Continuity (near 0 Ω).. Failure: No voltage on Pin 1 or 2 points to a wiring or ECM issue. No continuity on Pin 3 indicates a bad ground circuit.
• Sensor Signal Waveform (using oscilloscope) — expected: A clean square wave that changes frequency with engine RPM.. Failure: A flat line, erratic, or distorted waveform indicates a failing sensor or reluctor wheel issue.

Scan Tool Commands That Help

• Techstream: Utility -> All Readiness -> Check DTC Judgment Result — After a repair attempt and clearing codes, this function can be used during a confirmation driving pattern to see if the system's internal monitor has run and passed, confirming the fix without waiting for the MIL to potentially come back on.

Wiring & Ground Locations

• Bank 1 Intake Camshaft Position Sensor Connector — On the front timing cover, passenger side (Bank 1), upper position.. This is the connector for the sensor directly implicated by code P0340. It has three pins: Pin 1 (Power), Pin 2 (Signal), Pin 3 (Ground).
• Engine Ground Point — A primary engine ground point is located on the left side (driver's side) of the intake manifold.. The camshaft position sensor circuit requires a solid ground to function. A loose or corroded ground at this location can cause intermittent and difficult-to-diagnose signal issues for multiple engine sensors, including the one that triggers P0340.

Real Owner Repair Stories

• ft86club.com forum user (2013 Scion FR-S) — Check Engine Light with codes P0340 and P0341.
  ❌ Tried (didn't work) Swapping the Bank 1 and Bank 2 intake cam sensors (code did not move)., Testing the wiring harness for voltage (readings were normal).
  ✅ What actually fixed it The dealer performed the TSB procedure, measuring the sensor-to-reluctor gap and installing the correct shim. This permanently resolved the codes.
• ft86club.com forum user (2013 Scion FR-S) — Check Engine Light with P0340, rough idle, and stalling immediately after having the valve spring recall performed.
  ❌ Tried (didn't work) Initial dealer diagnosis which could not find a fault.
  ✅ What actually fixed it After escalating the issue, it was determined the technician likely damaged the camshaft position sensor or its wiring during the extensive recall service. The dealer replaced the Bank 1 intake camshaft position sensor under warranty, which resolved all symptoms.

OEM Part Supersession History

• SU003-00414 (Toyota) → 22056AA140 (Subaru) — These are equivalent OEM part numbers from Toyota and Subaru for the same sensor used on the shared FA20 engine platform.
  Heads up: These parts are cross-compatible. No known incompatibilities exist.

Model Year Variations Within This Range

• Early 2013: Vehicles produced before VIN JF1ZNAA1#D#721474 are prone to the camshaft sensor clearance issue. Later 2013 models and subsequent years had this corrected at the factory and are not covered by TSB S-SB-0013-14. For these later models, a P0340 code is more likely to be a failed sensor or wiring issue.