P0521 Alta 2-litre Diagnostic Trouble Code

P0521 Alta 2-litre code definition:
P0521 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Alta 2-litre.

P0521 Alta 2-litre is defined as Camshaft Position Sensor A Circuit Low. This means the CMP (camshaft position) sensor circuit on engine bank 1 sends an irregular reading. The PCM then uses this data to provide the right strategies for the fuel delivery and ignition timing of the engine.

Symptoms

Symptoms of a P0521 Alta 2-litre diagnostic trouble code may include:

Blown fuse (if applicable)
Engine surge
Reduction in engine performance, especially at low RPM levels
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
Faulty IMRC actuator relay (if equipped)
Dirty air cleaner element Damaged DPF

Common Misdiagnoses

TP Sensor Learn Not Complete Problem
Low Coolant Circuit Problem
Cruise Control System - Vehicle Accel Too High Problem
TFP Valve Position Switch-Drive Without Drive Ratio Problem
Problem

Repair Processes :

If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs. Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code P0521 Alta 2-litre is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before P0521 Alta 2-litre.

Fortunately, P0521 Alta 2-litre is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.