This procedure covers the removal and replacement of the crankshaft position sensor on the 2016-2021 Honda Civic 1.5L turbo engine, which monitors crankshaft speed and position for the engine control module.

Warnings

Tools required

Parts

• Crankshaft Position Sensor × 1 — 37500-5AA-A01 or equivalent OEM
• O-ring for sensor (if not included with sensor) × 1 — Use OEM specification

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Place wheel chocks behind rear wheels
4. Open hood and disconnect negative battery terminal
5. Raise front of vehicle using floor jack and support securely on jack stands
6. Remove front passenger side wheel for improved access (optional but recommended)
7. Remove engine under cover if equipped

Procedure

1. 1

   Locate the crankshaft position sensor
   From underneath the vehicle, locate the crankshaft position sensor on the lower front side of the engine block, just above the oil pan. The sensor is positioned near the crankshaft pulley area with a single electrical connector and one 10mm mounting bolt.
2. 2

   Disconnect electrical connector
   Press the tab on the electrical connector and carefully pull it away from the crankshaft position sensor. You may need to wiggle it gently to release it. Inspect the connector for corrosion or damage.
3. 3

   Remove sensor mounting bolt
   Using a 10mm socket and ratchet, remove the single mounting bolt securing the crankshaft position sensor to the engine block. Keep track of this bolt as it can easily fall into the engine bay.
4. 4

   Extract old sensor
   Carefully pull the crankshaft position sensor straight out from the engine block. The sensor has an O-ring seal that may cause slight resistance. If the sensor is stuck, gently twist it while pulling to break the seal. Do not pry against the engine block.
5. 5

   Inspect mounting hole and O-ring
   Check the sensor mounting bore in the engine block for debris, old O-ring material, or damage. Clean the area with a shop towel. If the old O-ring remained in the bore, carefully remove it. Inspect the new sensor to ensure the O-ring is properly seated in its groove.
6. 6

   Install new crankshaft position sensor
   Lightly lubricate the new O-ring with clean engine oil. Carefully insert the new crankshaft position sensor straight into the mounting bore, ensuring it seats fully against the engine block. Do not force it; the sensor should slide in smoothly.
   Torque spec

   Crankshaft Position Sensor10 Nm (7 lb-ft)
7. 7

   Install and torque mounting bolt
   Thread the 10mm mounting bolt by hand to ensure proper alignment, then tighten to the specified torque of 10.0 Nm (7.0 lb-ft) using a torque wrench. Do not over-tighten as this may damage the sensor body or threads.
   Torque spec

   Crankshaft Position Sensor10 Nm (7 lb-ft)
8. 8

   Reconnect electrical connector
   Push the electrical connector firmly onto the crankshaft position sensor until you hear or feel a positive click, indicating it is fully seated and locked in place. Gently tug on the connector to verify it is secure.
9. 9

   Reinstall under covers and wheel
   Reinstall the engine under cover if removed. Reinstall the front passenger wheel if removed and torque lug nuts to specification. Lower vehicle from jack stands.
10. 10

    Reconnect battery and initialize systems
    Reconnect the negative battery terminal. Perform power window auto-up/down initialization by holding each window switch up until fully closed, then continue holding for 2 seconds. Repeat for down position. Reset clock and radio presets as needed.

Reassembly

1. Ensure electrical connector is fully seated with audible click
2. Verify no tools or parts were left in engine bay or under vehicle
3. Double-check all fasteners are properly torqued

Verification

• Turn ignition to ON position without starting engine; check that check engine light illuminates then goes out (normal bulb check)
• Start the engine and verify it starts normally without extended cranking or rough running
• Allow engine to idle and confirm no check engine light or diagnostic trouble codes related to crankshaft position sensor (P0335, P0336, P0337, P0338, P0339)
• Test drive vehicle to verify normal operation, smooth acceleration, and no hesitation or stalling
• If check engine light remains on, use an OBD-II scanner to verify the crankshaft position sensor code has cleared

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