What does it mean?
P1326 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 2-Knock Control Limit Attained .
Symptoms
- MIL (check engine lamp) on
- Audible pinging or a metallic rattle under load, when climbing or accelerating hard
- Clear power loss, because ignition timing is being pulled back
- Higher fuel consumption
- Engine tends to run hot
- Rough running under heavy throttle, sometimes with hesitation
Likely causes
- Fuel with an octane rating below the engine's requirement, or old and contaminated fuel
- Carbon build-up on the piston crown and in the combustion chamber, raising effective compression and creating hot spots
- Overheating from low coolant, a blocked radiator, a failed thermostat or a weak water pump
- Lean mixture on that cylinder from a vacuum leak, a restricted injector or an intake gasket leak
- Spark plug of the wrong heat range, worn, or a plug with damage from earlier detonation
- Knock sensor reading mechanical noise, such as a worn timing chain, a loose heat shield or valvetrain rattle, as knock
- Base timing set too far advanced, or a non-standard calibration
How to fix it
- Read the knock retard value per cylinder in live data and confirm cylinder 2 is the one being pulled
- Fill with the correct octane fuel from a reliable pump and see whether the knock retard reduces
- Check coolant level, thermostat operation, radiator airflow and fan operation
- Smoke test the intake near cylinder 2 and check injector delivery and balance
- Remove the spark plug and check heat range, gap and any signs of detonation damage on the electrode and piston crown
- Carry out an induction or combustion chamber cleaning if carbon deposits are suspected
- Verify the knock sensor mounting torque and rule out mechanical noise sources before condemning the sensor