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2004 Silverado 4.3L V6 Cranks but Won't Start: P0463, P0135, P0622 Fault Codes Explained

Model: 04 silverado Fault Code: P0135 Posted: 2018-10-02 11:13

My 2004 Chevrolet Silverado 5-speed manual transmission with a 4.3L V6 engine is cranking but not starting. I've recently replaced the fuel filter (October 1), battery (October 1), and distributor cap/rotor (9 months ago). The gas gauge has been non-functional since I purchased the truck last year. The fuel pump activates and appears to be working properly, as confirmed by a video: https://youtu.be/q5itfrbvKiI. OBD2 diagnostic codes detected include P0463 (Fuel Level Sensor Circuit Malfunction), P0135 (Oxygen Sensor Heater Circuit Malfunction - Bank 1 Sensor 1), and P0622 (Ignition Key Cylinder or Ignition Switch Circuit). Despite these codes, the truck cranks but does not start. I'm seeking clarification on whether these specific fault codes are directly responsible for the no-start condition, and what steps to take next to diagnose the root cause.

Related fault codes
P0135P0463P0622
Comments (2)
Anonymous 2018-10-02 13:15

The P0463, P0135, and P0622 codes may not directly cause a crank-no-start issue. First, verify spark presence between the coil and distributor. If spark is confirmed, then test several spark plugs to rule out weak ignition or faulty components.

Anonymous 2018-10-02 23:12

Thanks for the response. Today I replaced the ignition lock cylinder (commonly referred to as the ignition switch) and reinstalled it. After that, the truck started immediately and ran smoothly—suggesting a loose or intermittent connection in the ignition system may have been the root cause.