P1326

What it means

P1326 on a Volkswagen means the engine control unit has reached the limit of how far it can retard the ignition timing on cylinder 2 to control knock. The control unit saw knock sensor signals for that cylinder that stayed above the threshold even after pulling timing back as far as it is allowed. This suggests either genuine detonation in cylinder 2 or a fault in the knock detection.

Symptoms

• Engine management light on
• Reduced power and flat acceleration
• Pinking or knocking noise under load
• Rough running or hesitation
• Poorer fuel economy

Possible causes

• Poor quality or incorrect fuel, with a lower octane rating than the engine requireslikely
• Carbon build-up in the combustion chamber or on the intake valves, raising the tendency to detonate in cylinder 2possible
• Faulty knock sensor, or damaged or corroded sensor wiring and connectorpossible
• Incorrect or loose knock sensor mounting, including wrong tightening torquepossible
• Ignition fault on cylinder 2, such as a worn spark plug or weak coilpossible
• Lean mixture or fuel delivery fault on cylinder 2, such as a faulty injector or an intake air leakpossible
• Mechanical engine noise mistaken for knock, such as piston slap or bearing wearrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting load, engine speed and temperature when the code set.
2. Ask about recent fuel used and fill with the correct grade of fuel if in doubt, as the engine specification varies by model.
3. Inspect the knock sensor wiring and connector for damage, chafing, oil contamination and corrosion.
4. Check the knock sensor is fitted correctly and tightened to the specified torque for the engine.
5. Inspect the spark plugs and ignition coils, paying particular attention to cylinder 2.
6. Check for misfires, fuel trim values and any intake air leaks to find a lean condition on cylinder 2.
7. Test the knock sensor signal and circuit resistance against the manufacturer data for the engine.
8. Inspect cylinder 2 with a borescope for carbon deposits, and carry out a compression test if mechanical noise is suspected.

How to fix

• Drain and replace poor fuel with the correct grade specified for the engine.
• Repair or replace damaged knock sensor wiring or connectors.
• Replace a faulty knock sensor and fit it to the correct torque.
• Replace worn spark plugs or a faulty ignition coil on cylinder 2.
• Repair air leaks or replace a faulty injector causing a lean mixture.
• Remove carbon deposits using a method suitable for the engine, or repair any mechanical fault found.

Can I keep driving?

Nearby codes

• P1325VolkswagenCylinder 1 Knock Control Limit Attained
• P1327VolkswagenCylinder 3 Knock Control Limit Attained