Decoding OBDII P1320 Code: Ignition Primary Circuit Malfunction Explained

Experiencing engine troubles with your Nissan or Infiniti? A P1320 code flashing on your OBDII scanner can be concerning. This diagnostic trouble code signals an issue within your vehicle’s ignition system, specifically pointing to a malfunction in the primary circuit. If you’re encountering a P1320 code, understanding its causes, symptoms, and troubleshooting steps is crucial to get your car running smoothly again. As an auto repair expert at autelfrance.com, I’m here to guide you through deciphering the P1320 code and getting to the root of the problem.

Understanding the OBDII P1320 Code

The P1320 code, as defined by the Society of Automotive Engineers (SAE), indicates an “Ignition Primary Circuit Malfunction.” This generic code, applicable to all OBDII compliant vehicles, often appears in Nissan and Infiniti models. The Engine Control Module (ECM) monitors the primary ignition circuit, which is the low-voltage side of the ignition system that controls the ignition coils. When the ECM detects an irregularity in the voltage, current, or signal frequency within this circuit, it triggers the P1320 code and illuminates the Check Engine Light.

Essentially, the P1320 code is a broad indicator of a potential electrical problem affecting the ignition coils’ ability to fire correctly. This can lead to a range of performance issues, from minor hesitations to significant engine misfires.

Common Symptoms Associated with P1320

When the P1320 code is present, you might observe several symptoms in your vehicle’s performance. These can vary in severity depending on the exact nature and location of the fault, but common signs include:

• Check Engine Light is illuminated: This is the most immediate and obvious symptom. The light may be constant or intermittent, depending on the frequency of the detected fault.
• Engine misfires: This is a very common symptom. Misfires occur when one or more cylinders fail to ignite the air-fuel mixture properly. You might feel this as a jerking or sputtering sensation, especially during acceleration or under load.
• Rough idling: The engine may idle unevenly, vibrating more than usual.
• Hesitation or lack of power: The engine may feel sluggish, especially when accelerating. You might notice a delay in response when you press the gas pedal.
• Reduced fuel economy: Misfires and inefficient combustion can lead to decreased fuel mileage.
• Engine stalling: In more severe cases, the engine might stall, particularly at idle or low speeds.
• Failed emissions test: Due to incomplete combustion, your vehicle may fail an emissions test.

It’s important to note that these symptoms are not exclusive to the P1320 code and can be associated with other engine problems. Therefore, a proper diagnosis using an OBDII scanner is crucial to confirm the presence of the P1320 code and guide further troubleshooting.

Potential Causes of P1320 Code

Several factors can contribute to a P1320 code. Diagnosing the root cause requires a systematic approach, checking each potential culprit:

1. Faulty Ignition Coil(s): This is the most frequent cause, particularly in older vehicles or those with high mileage. Ignition coils are responsible for generating the high voltage spark needed to ignite the fuel-air mixture. A failing coil can have an open or short circuit in its primary winding, triggering the P1320 code.

2. Wiring and Connector Issues: Damage, corrosion, or loose connections in the wiring harness leading to the ignition coils can disrupt the electrical signal. This includes:

   • Damaged wiring: Wires can be frayed, cracked, or broken due to age, heat, or physical damage.
   • Corroded connectors: Moisture and contaminants can cause corrosion within the electrical connectors, increasing resistance and disrupting the signal.
   • Loose connections: Connectors may become loose over time due to vibrations, leading to intermittent or complete signal loss.

3. Faulty ECM (Engine Control Module): While less common, a malfunctioning ECM can incorrectly interpret signals from the ignition system or fail to send the correct signals to the coils. This is usually diagnosed after ruling out other possibilities.

4. Spark Plug Issues: Although P1320 points to the primary circuit, issues with spark plugs can indirectly contribute to the problem. Worn or fouled spark plugs can increase the load on the ignition coils, potentially causing them to malfunction or triggering misfire codes that might be misinterpreted as primary circuit issues.

5. Distributor Problems (in older systems): In older vehicles equipped with a distributor ignition system, issues within the distributor, such as a faulty distributor cap, rotor, or pickup coil, can also lead to P1320 codes. However, modern vehicles predominantly use distributorless ignition systems.

Diagnosing and Troubleshooting P1320

Troubleshooting a P1320 code requires a methodical approach. Here’s a step-by-step guide:

1. OBDII Scan and Code Verification: Use an OBDII scanner to confirm the presence of the P1320 code and check for any other related codes. Record all codes present.

2. Visual Inspection: Carefully inspect the wiring and connectors leading to the ignition coils. Look for:

   • Visible damage: Frayed wires, cracked insulation, broken connectors.
   • Corrosion: White or greenish deposits on connectors or terminals.
   • Loose connections: Ensure all connectors are firmly seated.

3. Ignition Coil Testing:

   • Resistance Testing: Use a multimeter to measure the resistance of the primary and secondary windings of each ignition coil. Compare the readings to the manufacturer’s specifications. Significant deviations indicate a faulty coil. Note: As mentioned in the original query, unusual resistance readings can point to a coil issue. Inconsistent readings compared to specifications or other coils on the same engine warrant further investigation.
   • Coil Swapping (If applicable and safe for your vehicle): If you suspect a specific coil, you can swap it with a coil from a cylinder that is known to be functioning correctly. Clear the P1320 code and see if the misfire moves to the cylinder where you installed the suspected faulty coil. This can help isolate a bad coil.

4. Wiring Circuit Testing:

   • Continuity Test: Use a multimeter to check for continuity in the wiring between the ECM and the ignition coils. This ensures there are no breaks in the wires.
   • Voltage Test: Check for proper voltage at the ignition coil connectors when the ignition is turned on. Refer to your vehicle’s wiring diagram for specific voltage requirements.

5. Spark Plug Inspection: Remove and inspect the spark plugs. Look for signs of wear, fouling, damage, or incorrect gap. Replace spark plugs if necessary, especially if they are old or have exceeded their service life. Ensure you are using the correct type of spark plugs for your vehicle (as highlighted in the original query, using incorrect spark plugs like Bosch platinums when NGK is recommended can contribute to issues).

6. ECM Diagnosis (Last Resort): If all other components and wiring check out, and the P1320 code persists, a faulty ECM may be the issue. ECM diagnosis and replacement are complex and often require specialized tools and expertise. It’s recommended to consult a qualified mechanic for ECM-related issues.

Addressing the Original User’s Query

The original user described a scenario with a 1996 Infiniti I30 experiencing a P1320 code after replacing a #5 cylinder coil pack. Let’s address their questions based on the troubleshooting steps above:

1. “Should I replace the new coil pack (warranty covered) cause it could be bad, or the 5 others?” Yes, it’s definitely worth considering that the new coil pack might be faulty out of the box. Manufacturing defects can occur. Since it’s under warranty, replacing it is a logical first step and cost-effective. While the other older coils could also be nearing the end of their lifespan, focus on verifying the new coil first. Testing the resistance of the new coil compared to the old ones, and potentially swapping it with a known good coil, can help determine if it’s the culprit.

2. “Could the Bosch platinums be causing this? (they have less than 1000 miles)” Yes, incorrect spark plugs can absolutely contribute to ignition problems. While Bosch platinum plugs are generally reputable, it’s crucial to use the spark plug type specifically recommended for your 1996 Infiniti I30. Consult your owner’s manual or a reliable parts catalog to verify the correct NGK plug specification. Using the wrong plugs can lead to poor combustion, misfires, and increased stress on the ignition system. Switching back to the recommended NGK plugs is a prudent step.

3. “Should I look into replacing the IACV and MAF sensor?” The intermittent P0205 (IACV – Idle Air Control Valve) code is also present, suggesting a potential issue with the idle control system. While not directly related to the P1320 code, an IACV problem can cause rough idling and potentially exacerbate misfire symptoms. Similarly, a faulty MAF (Mass Air Flow) sensor can affect the air-fuel mixture, leading to various engine performance issues.

   • IACV: Investigating the IACV is worthwhile, especially given the P0205 code. Cleaning the IACV or replacing it might resolve idle-related issues.
   • MAF Sensor: Cleaning the MAF sensor (as the user mentioned) is a good maintenance practice. However, if problems persist, testing the MAF sensor’s output voltage and frequency can help determine if it’s faulty and requires replacement.

Regarding the eBay OEM coil packs: Purchasing OEM parts from reputable sources is generally recommended for critical engine components like ignition coils. While eBay can sometimes offer good deals, there’s also a higher risk of counterfeit or unreliable parts. If the price is significantly lower than established parts retailers, exercise caution and check seller reviews thoroughly. For a 305k mile car that you want to keep in good condition, investing in quality, genuine OEM or reputable aftermarket brand coil packs is advisable for long-term reliability.

Conclusion

The OBDII P1320 code indicates a malfunction in the ignition primary circuit, often pointing to issues with ignition coils, wiring, or connectors. A systematic diagnostic approach, starting with visual inspections and component testing, is essential to pinpoint the root cause. Addressing issues like incorrect spark plugs and considering related codes like P0205 (IACV) can also contribute to a comprehensive solution. By following the troubleshooting steps outlined, and potentially seeking professional assistance when needed, you can effectively resolve the P1320 code and restore your vehicle’s optimal performance. Remember to prioritize safety and consult your vehicle’s repair manual for specific procedures and specifications.