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1996 Cadillac Fleetwood 5.7L LT1 - Persistent P0335 and P0336 Codes After Water Pump Replacement and Engine Tuning

Model: 1996 cadillac fleetwood 5.7L Lt1 Fault Code: P0335 Posted: 2013-12-20 17:03

I recently replaced the leaking water pump and performed a full engine tune-up, including cap, rotor, wires, and plugs. Now I'm experiencing a check engine light with recurring codes P0335 and P0336. The engine cranks smoothly, runs well, has no misfires, and idles fine. I've already replaced the crankshaft position sensor, cleared the codes, but they return intermittently—sometimes appearing only on startup. The vehicle has 165,000 miles. Despite these symptoms, there are no performance issues. Any insights into what could be causing this recurring fault code? Note: The original crank sensor was aftermarket and did not resolve the issue.

Related fault codes
P0335P0336
Comments (5)
Anonymous 2013-12-21 09:24

Could you confirm whether your crankshaft position sensor is OEM or aftermarket? Aftermarket sensors are known to have reliability issues, especially in high-mileage LT1 engines.

Anonymous 2013-12-21 09:40

The data shows ignition timing at -17 degrees at idle—this is unusual and may indicate a faulty signal from the crank sensor or an underlying mechanical issue affecting sensor readings.

Anonymous 2013-12-22 06:58

Verify the electrical circuit to the crankshaft position sensor. If power and ground are intact, consider replacing it with an OEM sensor from the dealership—aftermarket units have a higher failure rate in older LT1 engines.

Anonymous 2013-12-22 07:53

Thanks for the input, Mohawkmtrs! It turns out that the timing chain was worn and causing inconsistent crankshaft position readings, which explains the P0335 and P0336 codes. Replacing the chain resolved the issue.

Anonymous 2014-01-17 11:55

333 wrote: \nMohawkmtrs, thanks for your help—turns out it was a worn timing chain causing faulty readings.\nThat's interesting! I'm seeing identical P0335 and P0336 codes in both my 1997 Z28 LT1 and a 1994 1371 engine. Before replacing the crankshaft position sensor, I'd like to confirm if the timing chain is actually worn—this could be a more cost-effective fix than replacing the sensor.