P1399 Chrysler: Understanding, Diagnosing, and Resolving This Fault Code

The P1399 Chrysler code is a generic type B code that indicates an intermittent problem in the ignition trigger circuit, specifically a synchronization issue between the crankshaft sensor and the camshaft sensor. This fault is specific to vehicles from the Chrysler group (including Dodge, Jeep, and Chrysler brands) and can cause symptoms ranging from a simple check engine light to starting problems and severe misfires. Understanding the source of this issue is crucial for performing the appropriate repairs and avoiding more serious engine damage.

What Does the P1399 Code Mean on a Chrysler?

The P1399 Chrysler error code literally translates to “Intermittent Ignition Trigger Problem.” The Powertrain Control Module (PCM) continuously monitors signals from the Crankshaft Position (CKP) sensor and the Camshaft Position (CMP) sensor. For the engine to run perfectly, the timing between these two signals must be precise. The P1399 code is triggered when the PCM detects an intermittent loss of synchronization between these two sensors for a duration longer than 3 seconds. This desynchronization prevents the PCM from accurately determining when to command fuel injection and ignition spark.

Common Symptoms of the P1399 Fault

Symptoms associated with the P1399 Chrysler code can vary in intensity. It is important to note that the intermittent nature of the fault can make diagnosis tricky, as symptoms may appear and disappear without apparent reason.

• Check Engine Light On: This is the most common symptom. The light may flash or remain on continuously.
• Starting Problems: The engine may have difficulty starting, requiring several turns of the key. In the most severe cases, the engine may not start at all.
• Engine Stalling: The engine may stall randomly, especially at idle or low speed.
• Misfires and Power Loss: You may experience hesitation, misfires, or significant power loss during acceleration.
• Irregular Idle: The idle speed may become unstable and fluctuating.

Possible Causes of the P1399 Code

Several components can be the source of the P1399 Chrysler code. The intermittent nature of the problem often points to faulty electrical connections or worn components.

• Faulty Camshaft Position Sensor (CMP): This is the most common cause. A faulty CMP sensor sends an incorrect or intermittent signal to the PCM.
• Faulty Crankshaft Position Sensor (CKP): Although less common, a bad signal from the CKP sensor can also trigger this code.
• Wiring and Connector Issues: Frayed, corroded, loose, or short-circuited wires in the CMP or CKP sensor circuits are a very common cause.
• Incorrect Engine Timing: A timing chain or belt that is slightly off can disrupt the alignment between the crankshaft and camshaft.
• Faulty PCM: Although rare, it is possible that the Powertrain Control Module itself is the cause.

Step-by-Step Diagnostic Procedure

Diagnosing a P1399 Chrysler code requires a methodical approach. It is recommended to use an OBD2 scanner capable of reading real-time data.

Step 1: Visual Inspection
Start with a thorough inspection of all wiring and connectors associated with the CMP and CKP sensors. Look for any signs of damage, corrosion, burning, or loose connections. Remember to check the wiring harness near hot or moving parts that could have damaged it.

Step 2: Sensor Testing
Using a multimeter, test the resistance and output signal of the sensors. The resistance values must match those specified by the manufacturer (usually available in a repair manual). An oscilloscope is the ideal tool for visualizing the signal waveform and detecting any intermittency.

Step 3: Checking Live Data
With your scanner, observe the live data from the CMP and CKP sensors while an assistant cranks the engine. Look for any signal loss or erratic values that coincide with the appearance of symptoms.

Step 4: Timing Verification
If the sensors and wiring seem good, it may be necessary to manually check the alignment of the timing marks to ensure the engine is in phase.

Solutions and Repairs

The repair depends entirely on the root cause identified during diagnosis.

• Replace the Camshaft Position Sensor (CMP): If testing confirms its failure, replacing it is the solution. Always use quality parts.
• Replace the Crankshaft Position Sensor (CKP): Proceed similarly if the CKP is identified as the source of the problem.
• Repair the Wiring: Repair or replace damaged wires. Use heat shrink tubing and quality solder to ensure a durable connection. Clean oxidized connectors with an appropriate product.
• Readjust the Timing: If the timing is off, it will be necessary to recalibrate the timing according to the manufacturer’s precise procedures.
• Clear the Code: After repair, clear the code with your OBD2 scanner and perform a road test to ensure the fault does not return.

Ignoring a P1399 Chrysler code can lead to complete engine failure, increased fuel consumption, and premature wear of the catalytic converter. Therefore, an accurate diagnosis is a wise investment for your vehicle’s longevity. If you do not feel comfortable with these procedures, entrust the diagnosis to a qualified mechanic with the necessary equipment and expertise to handle this complex electrical issue.