P1384 Knock sensor 1 P1385 Knock sensor 2

P1384 Knock sensor 1 P1385 Knock sensor 2

The error codes P1384 and P1385 

indicate a problem with the knock sensors, specifically Knock Sensor 1 and Knock Sensor 2. A knock sensor's job is to detect engine "knocking" or "pinging," which is caused by abnormal combustion. When it detects this, it sends a signal to the engine control module (ECM), which then adjusts the ignition timing to prevent potential engine damage. 

Common causes

• Defective knock sensors: The internal components of the sensors can fail over time, leading to inaccurate signals or no signal at all.
• Wiring issues: Damaged, corroded, or loose wiring in the knock sensor's circuit can cause intermittent or constant errors. This is a common failure point, especially if the wiring harness is exposed to engine heat or environmental factors.
• Improper installation: Over- or under-torquing the knock sensor during installation can cause it to function improperly. The sensors are sensitive and require a specific torque to work correctly.
• Engine damage: While less common, the ECM could be detecting actual engine knock due to other problems, such as a worn timing chain or an issue with the air-fuel mixture. 

Symptoms of a faulty knock sensor

• Illuminated check engine light: The most common symptom is the check engine light turning on and storing the P1384 and P1385 codes.
• Reduced engine performance: The ECM will often retard the ignition timing as a precaution. This results in sluggish acceleration and poor engine performance.
• Engine knocking or pinging: In some cases, the sensor may fail in a way that prevents the ECM from detecting actual engine knock, which you may then hear as a rattling or metallic sound.
• Increased fuel consumption: The adjusted ignition timing can negatively impact fuel efficiency. 

Diagnosis and repair

1. Visual inspection: Start by visually inspecting the knock sensors and their wiring harnesses for any obvious damage or loose connections.
2. Test the sensors: A mechanic can test the sensors' electrical signal with a multimeter or oscilloscope to determine if they are sending the correct voltage to the ECM.
3. Replace the sensors: If the sensors are confirmed to be faulty, they should be replaced. Some vehicles have a single sensor, while others have two (one for each engine bank). It is often recommended to replace both sensors at the same time if they are on the same engine bank.
4. Clear codes and test drive: After replacement, the codes should be cleared from the ECM, and the vehicle should be test-driven to confirm the repair has fixed the issue. 

Cost of repair

The total cost to replace knock sensors can range from $150 to $500 or more, depending on the vehicle's make and model. The sensors themselves are relatively inexpensive, costing anywhere from $30 to over $100. The main cost factor is labor, as the sensors can be difficult to access on many engines, often requiring the removal of other components.