04 buick ranier rough idle almost stalls

DTC P0016 - Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)
The crankshaft position sensor (CKP) and Camshaft position sensor (CMP) work in harmony to control the spark/fuel delivery and timing. They both consist of a reluctor, or tone, ring which passes over a magnetic sensor, which generates a voltage, indicating position.

The crankshaft sensor is part of the primary ignition system and functions as the "trigger". It detects the position of the crankshaft relays that information on to the PCM or the ignition module (depending on the vehicle) to control spark timing. The Camshaft position sensor detects the position of the camshafts and relays the information to the PCM. The PCM uses the CMP signal to identify the beginning of the injector sequence. What ties these two shafts and their sensors together is the timing belt or chain. The cam and crank should be precisely timed together. If the PCM detects that the Crank and Cam signals are out of time by a specific number of degrees, this P0016 code will set.

Symptoms of a P0016 will or may include:
Malfunction Indicator Lamp (MIL) illumination
The engine may run but with reduced performance
The engine may crank but not start
The engine may exhibit a rattle near the harmonic balancer indicating the tone ring is damaged
The engine may start and run, but poorly

Causes may include:
Timing chain stretched, or timing belt skipped a tooth due to wear
Misalignment of timing belt/chain
Tone ring on crankshaft slipped/broken
Tone ring on camshaft slipped/broken
Bad crank sensor
Bad cam sensor
Damaged wiring to crank/cam sensor
Timing belt/chain tensioner damaged

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