The P033A: Knock Sensor 4 Circuit (Bank 2) code indicates an issue with knock sensor 4 on bank 2. Knock sensors detect engine knock (pre-detonation) and send signals to the engine control module (ECM) to adjust engine timing and prevent engine damage. When this code is triggered, it means that the ECM is detecting a problem in the circuit of knock sensor 4, possibly due to a faulty sensor, circuit issues, or wiring problems.
P033A – Quick Overview
Meaning | P033A: Knock Sensor 4 Circuit (Bank 2) |
Is it serious? | Yes, this code can prevent the ECM from detecting engine knock, leading to potential engine damage if not resolved. |
Possible causes | – Faulty knock sensor 4 – Circuit issues – Wiring problems |
How to diagnose? | – Test knock sensor 4 – Inspect circuit and wiring – Replace sensor if necessary |
P033A Meaning
The P033A: Knock Sensor 4 Circuit (Bank 2) code means that knock sensor 4 on bank 2 is either malfunctioning or the circuit is experiencing issues that are preventing the ECM from receiving proper signals. The knock sensor helps the ECM detect engine knock and adjust timing accordingly. If this sensor fails, the engine may not be protected from damaging pre-detonation events.
Step-by-step diagnostic guide
Follow these steps to diagnose and resolve the P033A code by addressing potential causes one by one.
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for any other related codes. These may provide additional clues about the issue. | OBD-II Scanner |
Inspect Knock Sensor 4 | Visually inspect knock sensor 4 for any signs of damage, corrosion, or poor mounting. Ensure it is securely attached and properly connected. | Flashlight, Safety Gloves |
Test Knock Sensor 4 | Use a multimeter to test knock sensor 4’s performance. Compare the readings to the manufacturer’s specifications to ensure it is operating correctly. | Multimeter, Manufacturer’s Specifications |
Inspect Circuit and Wiring | Check the wiring and circuit leading to knock sensor 4 for signs of wear, loose connections, or corrosion. Repair or replace any damaged wiring. | Flashlight, Wiring Repair Kit |
Replace Knock Sensor if Necessary | If knock sensor 4 is not functioning properly or if the readings are outside the manufacturer’s specifications, replace it. | Replacement Knock Sensor, Safety Gloves |
Clear the Code and Test Drive | After completing repairs, clear the P033A code using an OBD-II scanner. Test drive the vehicle to ensure the issue is resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
Recheck for Codes | After the test drive, re-scan the vehicle to ensure the P033A code has not returned. If it does reappear, further diagnosis may be necessary. | OBD-II Scanner |
This guide will help you diagnose and resolve the P033A code, ensuring that knock sensor 4 on bank 2 operates correctly and helps protect your engine from knock and detonation.

Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)