P1320
Ignition Signal Primary
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The P1320 code is one of the most common Nissan-specific trouble codes and indicates that the ECM is not receiving the expected ignition signal from the primary ignition circuit. On Nissan vehicles, the ECM sends a signal to the ignition coil's power transistor, which then switches the coil's primary circuit on and off to generate spark. When this feedback signal is missing or abnormal, the ECM sets P1320.
The overwhelming majority of P1320 cases are caused by one or more failing ignition coils. Even if a coil appears to work during normal driving, it may have elevated resistance that causes it to fail under heavy load or high temperatures. This is why many Nissan technicians recommend replacing all ignition coils at once — especially on higher-mileage vehicles — since the remaining coils often follow shortly after.
For most Nissan engines, replacing ignition coils is a very DIY-friendly repair. On inline-4 engines, the coils sit right on top of the engine and are held in place with a single bolt each. V6 engines may require removing the intake manifold to access the rear bank coils. Individual coils cost $20–$50 each, and a full set of six runs $120–$250 in parts. Professional repair typically costs $150–$500 depending on engine accessibility and how many coils need replacement.
Severity
Symptoms
- •Engine misfires or runs rough
- •Noticeable loss of power during acceleration
- •Engine may stall at idle
- •Difficulty starting the vehicle
- •Check engine light flashing or steady
- •Engine vibration felt through steering wheel or seat
Likely Causes
One or more ignition coils have developed high internal resistance or intermittent failure, which is the most common trigger for P1320 on Nissan engines. The coil may test fine cold but fail under heat or load.
The wiring between the ECM and ignition coils has high resistance, is corroded, or has a poor connection at the coil connector, preventing the proper ignition signal from reaching the coil.
On some Nissan engines (especially older VQ and VG series), the power transistor that amplifies the ECM's ignition signal can fail, affecting all cylinders on that bank.
A failing crankshaft position sensor may provide an inconsistent reference signal that disrupts the ignition timing signal, indirectly triggering P1320.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace failed ignition coil(s) — often best to replace all at once on higher-mileage engines
- Inspect and repair wiring and connectors between ECM and ignition coils
- Replace the power transistor unit if applicable to your engine
- Check and replace spark plugs if worn or fouled