P0340 on 2017-2018 Chevrolet Trax: Camshaft Sensor Circuit Causes and Fixes

What's Unique About the 2017-2018 Chevrolet TRAX

For the 2017-2018 Chevy Trax with the 1.4L Ecotec engine, a key factor setting it apart is its sensitivity to battery voltage. General Motors issued a Technical Service Bulletin (TSB #PIP5482B) that directly links code P0340 (along with P0335 and P0365) to potential battery issues, especially on vehicles with low mileage or that have been parked for extended periods. This means a weak or failing battery can trigger this camshaft sensor code after just two consecutive engine starts with a low state of charge. This issue is also common on platform mates like the Buick Encore and Chevy Sonic that share the same 1.4L LUV engine.

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 hard to start or cranks for 5-7 seconds before starting
• Engine cranks but won't start at all
• Engine stalls, especially at idle or when coming to a stop
• Rough running or misfiring
• Noticeable lack of acceleration and reduced engine power
• Poor fuel economy
• Transmission shifting problems

Most Likely Causes

1. Weak or Failing Battery 🔴 High Probability → Shop Vehicle Battery A specific GM Technical Service Bulletin (#PIP5482B) for the 2017-2018 Trax explicitly directs technicians to perform a battery inspection when P0340, P0335, and P0365 are present together, 🎬 See how low voltage triggers these specific cam and crank codes. indicating a known sensitivity to low voltage causing sensor circuit faults. This is especially common on vehicles that sit for extended periods.
   How to confirm: Use a multimeter to check battery voltage (should be ~12.6V with engine off). Take the vehicle to an auto parts store for a free, comprehensive load test using a professional tester like the GR8 / EL-50313-20 mentioned in the TSB.
   Typical fix: Replace the vehicle's battery. Ensure the new battery is fully charged before installation.
   Est. part cost: $150-$250
2. Faulty Camshaft Position Sensor (Intake) 🔴 High Probability → Shop Engine Camshaft Position Sensor Like any electronic sensor, the camshaft position sensor can fail over time due to heat cycles and vibration. It's a common replacement part for this engine.
   How to confirm: After confirming the battery and wiring are good, the sensor is the next logical part. It is located on the top, rear side of the valve cover (intake side). It can be tested with a multimeter by checking for 5V reference, ground, and a changing signal voltage while cranking, but replacement is often faster for a DIYer.
   Typical fix: Replace the camshaft position sensor 'A' (intake). Ensure the old O-ring comes out with the old sensor.
   Est. part cost: $25-$60
3. Damaged Wiring or Connector 🟡 Medium Probability The wiring harness and connector for the sensor can become brittle, corroded, or damaged from engine heat and vibration. The plastic locking tab on the connector is a common failure point. 🎬 Check out this quick breakdown of common P0340 causes and fixes.
   How to confirm: Visually inspect the wiring leading to the camshaft position sensor for any signs of cracking, fraying, or melting. Check that the connector is securely plugged in, the locking tab is engaged, and the terminals inside are free of corrosion.
   Typical fix: Repair the damaged section of wire or replace the pigtail connector. The connector has 3 wires.
   Est. part cost: $15-$40

Rare But Worth Checking

• Stretched Timing Chain: → Shop Engine Timing Chain While less common, if the battery, sensor, and wiring are all confirmed good, a stretched timing chain could cause the cam/crank correlation to be off, triggering this code. This is a more significant mechanical issue often accompanied by rattling noises.
• Faulty Battery Sensor: → Shop Vehicle Battery In some cases, the battery itself may test fine, but a faulty battery monitoring sensor (located on the negative battery terminal) can cause incorrect voltage readings and electrical issues, leading to various codes including P0340.
• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is very rare. The ECM should only be considered after all other possibilities, including mechanical timing and all circuit tests, have been exhaustively ruled out by a professional.
• Weak Key Fob Battery: → Shop Vehicle Battery One owner on a Reddit forum reported that a weak key fob battery caused a no-start condition with codes P0335, P0340, and P0365. The issue was resolved by replacing the key fob battery, as the car's immobilizer system was likely affected.

Diagnosis Steps

1. Read the codes with an OBD-II scanner. Note all codes present, especially P0335, P0365, or P1101, as they reinforce the possibility of a battery-related issue.
2. Perform a Battery/Charging System Test. This is the most critical first step based on TSB #PIP5482B. Check the battery voltage with a multimeter (should be ~12.6 volts engine off, ~14.0-14.7V engine running). Have the battery professionally load-tested, even if it's new.
3. If the battery is weak or fails the load test, replace it. Clear the codes, start the vehicle twice, and drive to see if P0340 returns.
4. If the battery is good, locate the Camshaft Position Sensor 'A' (Intake). It is on the rear of the valve cover (towards the firewall). Visually inspect its connector and wiring for damage, corrosion, or looseness. Ensure the gray locking tab on the connector is secure.
5. Test the Sensor Circuit (Optional, for advanced DIY). Disconnect the sensor. With the key on, use a multimeter to check the connector terminals. You should find approximately 5 volts (reference), a good ground (near 0 volts), and another 5 volts on the signal wire. If these voltages are incorrect, the problem is in the wiring or ECM.
6. If the wiring and circuit voltages appear correct, the most likely cause is a failed camshaft position sensor. Replace the sensor. Be sure to remove the old O-ring.
7. Clear the code with the scanner and test drive the vehicle. If the code persists, a more advanced diagnosis of the timing system or ECM may be required, which is best left to a professional.

Parts You'll Likely Need

• Battery (OEM #ACDelco Gold 47AGM (Group Size H5/L2/47)) — A known cause of P0340 on this vehicle per GM TSB #PIP5482B.
  Trusted brands: ACDelco, DieHard, Interstate
  OEM price range: $200-$300
  Aftermarket price range: $150-$250
• Camshaft Position Sensor (OEM #12674702 (Supersedes 55566932)) — This is the sensor that reports the camshaft's position. It is the most common part to fail if the battery is healthy. Note: This part number is also used for the crankshaft position sensor on some GM models, but fits the camshaft position sensor on this application.
  Trusted brands: ACDelco (GM Genuine), Delphi, NTK, Bosch
  OEM price range: $40-$60
  Aftermarket price range: $25-$45
• Camshaft Position Sensor Connector Pigtail (OEM #Standard Motor Products S2820 (Aftermarket)) — The original connector can become brittle and fail, requiring a new pigtail to be spliced in.
  Trusted brands: Standard Motor Products, Dorman
  OEM price range: N/A
  Aftermarket price range: $15-$40

Related Codes That Often Appear With This One

• P0335 — This is the code for the Crankshaft Position Sensor circuit. TSB #PIP5482B explicitly mentions it alongside P0340, as a weak battery can affect both sensor circuits simultaneously.
• P0365 — This code is for the Camshaft Position Sensor 'B' circuit (exhaust). It is also mentioned in TSB #PIP5482B and can be triggered by the same battery issues. Seeing P0340 and P0365 together strongly suggests a systemic problem rather than two independent sensor failures.
• P1101 — This code relates to the calculated airflow being out of range. On some GM 1.4L engines, a cluster of sensor codes including P0340 can appear alongside P1101, again pointing towards a systemic electrical issue like a bad battery or ground.

Technical Service Bulletins (TSBs) & Recalls

• PIP5482B: Advises technicians to perform a battery inspection/test when diagnosing DTCs P0335, P0340, or P0365, noting the cause can be a low state of charge during two consecutive starts.

Platform-Specific Known Issues

• GM Technical Service Bulletin #PIP5482B indicates that a Check Engine Light with DTCs P0335, P0340, or P0365 may be caused by a battery issue. The bulletin advises technicians to perform a battery inspection and test using a GR8 / EL-50313-20 tester as a primary diagnostic step.

Mechanic-Grade Diagnostic Values

• Camshaft Sensor Connector - Reference Voltage — expected: ~5V DC. Failure: Significantly lower or no voltage indicates a wiring or ECM issue.
• Camshaft Sensor Connector - Signal Voltage — expected: ~5V DC. Failure: Significantly lower or no voltage indicates a wiring or ECM issue.
• Camshaft Sensor Connector - Ground Circuit — expected: ~12.6V DC (Battery Voltage). Failure: Low or no voltage indicates a bad ground connection.
• Alternator AC Ripple Voltage — expected: < 0.5V AC. Failure: Voltage above 0.5V AC indicates failing alternator diodes, which can create electrical noise and disrupt sensor signals.

Scan Tool Commands That Help

• GDS2 / Professional Scan Tool: Crankshaft Position Variation Learn (Cam/Crank Relearn) — After replacing the crankshaft sensor, camshaft sensor, or timing components, or if the ECM has been replaced or reprogrammed. A failure to complete this procedure can indicate a problem with the cam or crank sensor signals. The procedure requires the engine to be at operating temperature and for the user to rev the engine to a specified RPM when prompted by the tool.

Wiring & Ground Locations

• G103 — On the cowl/firewall in the engine compartment, often located above the brake booster.. This is a primary ground point for the Engine Control Module (ECM) and Body Control Module (BCM). A loose or corroded connection here can cause erratic sensor readings and false codes, including P0340.
• G105 — At the left front of the engine compartment, often near the cooling fan relays or frame cross rail.. This ground serves the Engine Control Module (ECM) and Transmission Control Module (TCM). A poor ECM ground directly impacts its ability to correctly interpret sensor signals.

OEM Part Supersession History

• 12627185, 12632872 → 12674702 — Standard part revision and consolidation by the manufacturer.
  Heads up: The current part, 12674702, is often listed by retailers as a 'Crankshaft Position Sensor'. However, it is the correct part for the Camshaft Position Sensor on the 1.4L Trax engine. This can cause confusion during ordering, but the sensor is physically and electronically identical for both locations on this application.

Model Year Variations Within This Range

• 2017-2018: There are no significant mechanical or electrical differences affecting the diagnosis of P0340 between the 2017 and 2018 Chevrolet Trax. The 2017 model year was a major refresh, but the 2018 model carried over the same 1.4L engine and electronics.