← Back to list

Persistent P0336 Code on 2001 Pontiac Grand Am SE V6: Causes and Solutions

Model: 2001 Pontiac Grand Am SE V6 Fault Code: P0336 Posted: 2020-04-01 16:02

The P0336 diagnostic trouble code has reappeared after being cleared following AC bypass pulley installation. The vehicle previously exhibited intermittent misfires, which resolved after the pulley replacement. Since then, the car runs smoothly—no misfires, good fuel economy, and normal performance. However, the P0336 code returns consistently. The 2001 Pontiac Grand Am SE V6 is equipped with a 3.4L engine and uses two crankshaft position sensors: one behind the harmonic balancer (hall effect sensor) and another in the engine block (magnetic VRS sensor). The P0336 code specifically relates to the hall effect crank sensor, which is critical for engine timing and misfire monitoring. Despite clearing the code after pulley installation and observing normal operation for four days, it reappeared on day five. This suggests a persistent underlying issue—possibly related to wiring harness damage behind the harmonic balancer or degraded sensor signal integrity. The vehicle has no hard starting issues or performance loss, but the code remains active. Recommended next steps: Have a certified technician perform diagnostic testing of both crank sensors—including power, ground, and signal circuit checks—at the PCM and ignition control module connectors. A scope test may be needed to verify sensor signal consistency. If wiring harnesses are damaged (e.g., due to serpentine belt wear or proximity to power steering pump), removal of the power steering pump may be required for proper testing. Note: The P0336 code is not typically caused by engine misfires alone, but rather indicates a fault in sensor signal detection. A thorough diagnostic is essential before assuming mechanical failure.

Related fault codes
P0336
Comments (15)
Anonymous 2020-04-01 20:17

Common causes of the P0336 code include: a faulty crankshaft position (CKP) sensor, a damaged reluctor ring with missing teeth or debris, a dislodged or stripped reluctor ring, chafed wiring harness causing short circuits, or an open circuit in the CKP sensor wiring. For detailed troubleshooting, refer to official OBD2 diagnostic resources.

Anonymous 2020-04-01 20:32

Did you observe the P0336 code before any repairs were performed? Were there prior misfire symptoms? What specific issues are present—such as hard starting or rough idling?

Anonymous 2020-04-01 20:32

Is this a 3.4L engine configuration? This is relevant to the sensor setup and diagnostic behavior.

Anonymous 2020-04-02 08:26

Ensure the technician performs a full diagnostic scan, including live data monitoring of crankshaft position sensors and related circuits.

Anonymous 2020-04-02 16:28

Yes—this is a 3.4L engine. Misfires occurred before the AC bypass pulley was installed. The original diagnosis from the technician was P0336. After installing the bypass pulley, misfires stopped and the car ran well. The code was cleared. It remained gone for four days before reappearing on day five. This strongly suggests a persistent issue with the rear crank sensor or wiring behind the harmonic balancer.

Anonymous 2020-04-02 16:29

The vehicle starts easily, runs smoothly, and maintains good fuel efficiency and power—no noticeable performance issues.

Anonymous 2020-04-02 19:02

Was the P0336 code confirmed by the technician? What specific actions were taken to resolve misfires? Was the hall effect crank sensor behind the harmonic balancer replaced? The P0336 is typically triggered by a fault in the 24x hall-effect crank sensor. For intermittent faults, it's essential to reproduce the condition and perform live data analysis of both cam and crank sensors. A wiring harness issue behind the harmonic balancer could be causing signal degradation. Testing at the PCM or ignition module connector may reveal problems. Please clarify these details for accurate diagnosis.

Anonymous 2020-04-03 08:00

The 24x hall-effect sensor is used primarily for misfire monitoring and engine timing in OBD2 systems. Damaged wiring harnesses—especially near the power steering pump—can interfere with signal integrity. A scope test at the ignition module connector or harness junction may help identify intermittent faults.

Anonymous 2020-04-03 10:26

Misfires occurred before the AC bypass pulley was installed, coinciding with failing AC compressor bearings and a metallic serpentine belt noise. After installing the bypass pulley, misfires ceased and performance improved significantly. The original scan showed P0336. The code was cleared and remained gone for four days before returning on day five. Could damaged wiring behind the harmonic balancer be the root cause? Thanks for your detailed input!

Anonymous 2020-04-03 10:28

Neither of the two crankshaft sensors has been replaced—both have been tested and appear functional.

Anonymous 2020-04-03 10:29

The vehicle continues to run fine with no misfires. However, the P0336 code persists despite normal operation.

Anonymous 2020-04-03 12:32

The 2001 Pontiac Grand Am SE V6 has two crankshaft sensors: one behind the harmonic balancer (3-wire hall effect sensor) and another in the engine block (2-wire VRS magnetic sensor). The P0336 code is triggered by a fault in the 3-wire hall-effect sensor. It's essential to test for proper voltage, ground, and signal integrity in both circuits. This sensor connects directly to the PCM; the other connects to the ignition control module. In some cases, damaged wiring harnesses behind the harmonic balancer cause intermittent P0336 faults. The power steering pump may need removal to access the harness for testing. A back-probe test at the connector or PCM is recommended.

Anonymous 2020-04-03 20:14

Excellent technical insight—thank you! I will have the technician perform both sensor circuit tests and live data monitoring as suggested.

Anonymous 2020-04-03 20:29

It's best to take the vehicle to a certified OBD2 diagnostic shop with experience in testing hall-effect crank sensors. Proper equipment and knowledge are essential for accurate diagnosis and repair.

Anonymous 2020-04-03 20:37

I will follow your advice and visit a certified technician for full sensor diagnostics. Thank you again for the helpful guidance!