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

P1399 Audi is a specific error code related to the engine management system, more precisely to the camshaft timing. When this fault code appears on your diagnostic tool, it indicates a synchronization problem between the crankshaft and the camshaft, a crucial element for the proper operation and performance of your Audi engine. This code is often accompanied by an illuminated check engine light on your dashboard and can lead to power loss, misfires, or even a limp mode to protect the engine. Understanding the origin of this problem is essential to perform the appropriate repairs and avoid more serious and costly damage.

What is the P1399 fault code on an Audi?

The generic code P1399 Audi translates to “Camshaft/Crankshaft Timing Misalignment – Performance Range”. It means that the Powertrain Control Module (PCM/ECU) has detected an abnormal difference, or a performance range outside specifications, between the signal from the crankshaft position sensor and that from the camshaft position sensor(s). These two signals must be perfectly synchronized so that the ECU can command fuel injection and spark plug ignition at the precise moment, ensuring optimal combustion. A misalignment, even a minor one, can therefore disrupt the entire combustion cycle.

Common Symptoms of the P1399 Fault

When the P1399 Audi code is stored in the ECU’s memory, several symptoms can alert the driver. It is important not to ignore them to prevent potential collateral damage.

• Check Engine Light: The most obvious symptom is the illumination of the “check engine” warning light on the dashboard.
• Engine Misfire: You may experience misfires, hiccups, or a significant loss of power, especially during acceleration.
• Irregular Idle: The engine may have an unstable, rough idle or shake when in neutral.
• Starting Difficulties: In some cases, the poor timing can make starting the vehicle longer and more difficult.
• Increased Fuel Consumption: Inefficient combustion often results in excessive fuel consumption.
• Limp Mode Activation: To protect the engine, the ECU may activate a fail-safe mode that limits engine power and RPM.

Potential Causes of the P1399 Code on Audi

Several mechanical and electrical components can be the source of the P1399 Audi fault. A methodical diagnosis is necessary to identify the root cause.

• Timing Belt or Timing Chain Problem: This is a common cause. A timing belt that has jumped one or more teeth or a stretched chain will immediately desynchronize the camshafts and the crankshaft.
• Faulty Camshaft Position Sensor: The sensor itself may be defective, providing an erroneous or intermittent signal to the ECU.
• Faulty Crankshaft Position Sensor: Similar to the previous one, a bad signal from the CKP sensor can mislead the ECU.
• Wiring or Connector Issues: Damaged, loose, corroded, or short-circuited wires between the sensors and the ECU can interrupt or distort the signal.
• Problem with the Pulley or Sprocket: On some engines, a faulty reluctor wheel or tensioner can affect the timing.
• Internal Engine Problem: Although rarer, serious internal mechanical issues (e.g., a bent cam) can be the cause.

Step-by-Step Diagnostic Procedure

Diagnosing a P1399 Audi requires a logical approach. It is highly recommended to consult an experienced mechanic or use a capable diagnostic tool.

1. Code Reading and Live Data: Use an OBD2 scanner to confirm the presence of the P1399 code. Clear it and drive the vehicle to see if it returns immediately. Observe the live data from the CMP and CKP sensors to check their synchronization and consistency.

2. Visual Inspection: Carefully inspect the wiring and connectors of both sensors. Look for any signs of damage, corrosion, burning, or loose connections.

3. Sensor Testing: Using a multimeter, test the resistance and voltage of the position sensors (according to the manufacturer’s specifications for your Audi model). A faulty sensor will need to be replaced.

4. Checking Mechanical Timing: This is the most critical step. It often requires setting the engine to Top Dead Center (TDC) and verifying the alignment of the marks on the crankshaft pulley and camshaft sprockets. If the belt has jumped teeth, it will be necessary to replace it along with the tensioner pulleys.

Recommended Solutions and Repairs

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

• Replacing a Faulty Sensor: If the diagnosis points to the camshaft or crankshaft position sensor, replace it with an OEM quality or equivalent part.
• Repairing Wiring: Repair or replace any damaged wiring harness and ensure all connectors are clean and securely fastened.
• Replacing the Timing Belt/Chain: If the mechanical timing is incorrect, it is imperative to replace the timing belt (along with the complete kit including pulleys and water pump if recommended) or resolve the chain issue. This is a complex and costly operation, but vital to avoid engine failure.
• Resetting the ECU: After any repair, clear the fault codes with your diagnostic tool and perform a road test to ensure the problem is resolved and the code does not reappear.

Ignoring a P1399 Audi code can have disastrous consequences, including piston-to-valve contact if the misalignment is significant, leading to an extremely expensive repair. Early diagnosis and repair by a professional are the best guarantees for the longevity of your Audi engine.