P21A5 Volkswagen Export Diagnostic Trouble Code

P21A5 Volkswagen Export code definition:
P21A5 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Volkswagen Export.

P21A5 Volkswagen Export is triggered when the bank 1 camshaft position sensor doesn't match the signal from the crankshaft position sensor. 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 P21A5 Volkswagen Export diagnostic trouble code may include:

Poor acceleration
Cherry red hot catalytic converter
Possible spark knock (detonation / pre-ignition)
Engine surge

Possible Causes :

Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.

Common Misdiagnoses

Vehicle Speed Output Circuit Problem
Cruise Control Servo Indicates Low Problem
A/C System High Pressure High Temperature Problem
PCM Stack Overrun Problem
Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors. Pull the connectors apart and carefully look at the terminals (the metal parts) inside the connectors. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code P21A5 Volkswagen Export 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 P21A5 Volkswagen Export.

Fortunately, P21A5 Volkswagen Export is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.