P2338 OBD-II Trouble Code: Cylinder #3 Above Knock Threshold

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P2338 code

P2338 is a diagnostic trouble code (DTC) for "Cylinder #3 Above Knock Threshold". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P2338 DIAGNOSTIC Get a fair and transparent estimate upfront

P2338 Code Definition

A P2338 code is a generic powertrain code related to an ignition-related problem, such as an engine misfire. It appears when the engine control module (ECM) has received a voltage reading outside the allowed variances from engine cylinder number three.

The P2338 code may be related to:

  • P0324: Knock Control System Error
  • P2336: Cylinder #1 Above Knock Threshold
  • P2337: Cylinder #2 Above Knock Threshold
  • P2339: Cylinder #4 Above Knock Threshold
  • P2340: Cylinder #5 Above Knock Threshold
  • P2341: Cylinder #6 Above Knock Threshold
  • P2342: Cylinder #7 Above Knock Threshold
  • P2343: Cylinder #8 Above Knock Threshold
  • P2344: Cylinder #9 Above Knock Threshold
  • P2345: Cylinder #10 Above Knock Threshold
  • P2346: Cylinder #11 Above Knock Threshold
  • P2347: Cylinder #12 Above Knock Threshold

What the P2338 Code Means

A knock sensor is a one-wire sensor that helps the engine control module (ECM) “hear” engine noise to help determine proper function through the use of a low-voltage signal. When the ECM receives a voltage reading from the knock sensor in cylinder 3 that varies 10% or more from the set voltage parameters, a P2338 code will be stored. If an abnormal reading is received by the ECM, it can adjust engine timing to reduce possible damage.

What Causes the P2338 Code?

A P2338 code can be caused by:

  • Incorrect air/fuel mixture
  • Damaged or defective knock sensor
  • Damaged or frayed wiring
  • Damaged or broken connectors

What are the Symptoms of the P2338 Code?

  • Warning or Check Engine Light may illuminate
  • Vehicle hesitates during acceleration
  • Decreased fuel efficiency
  • A loss in vehicle power or decreased acceleration
  • Spark knock

How Does a Mechanic Diagnose the P2338 Code?

  • Utilize an OBD-II scanner to check for a stored P2338 code
  • Visually inspect all wiring and connectors for damage
  • Check engine oil levels and oil quality
  • Listen to the engine for excessive noise
  • Check oil pressure
  • Test individual knock sensor
  • Clear the code, test drive the system, and rescan to see if the code appears

Common Mistakes when Diagnosing the P2338 Code

Because the knock sensor is essentially a microphone for the engine, it is possible that a sensor may be “hearing” an issue with a different cylinder and storing an inaccurate code. Ensure that all cylinders are checked for possible damages before returning to the road.

How Serious is the P2338 Code?

Since a vehicle’s knock sensors can decrease acceleration, this can impacting drivability and may possibly signify a more serious problem. This is considered a potentially serious code and it is recommended to have the vehicle immediately diagnosed and repaired.

What Repairs can Fix the P2338 Code?

  • Replace any damaged, frayed, shorted, or burned wiring or connectors
  • Change engine oil and ensure that it is full
  • Perform a manual engine oil pressure test
  • Replace affected sensor
  • Test electrical circuits (continuity and resistance)

Additional Comments for Consideration Regarding the P2338 Code

As not all knock sensors are easy to access, so test and diagnose all other sensors to avoid unnecessary engine removal or repair. Also, ensure that care is taken when removing knock sensors, as the coolant passage can cause severe burns.

Need help with a P2338 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

P2338
trouble codes
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P2338 code.

SCHEDULE P2338 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

5,361

Rating Summary
4,946
200
50
30
135
4,946
200
50
30
135

William

16 years of experience
64 reviews
William
16 years of experience
Jeep Grand Cherokee - Check Engine Light is on - Denver, Colorado
Couldn’t be happier with my experience with William. Will happily recommend him to everyone and will definitely be using him again. Fantastic service.

Andrian

31 years of experience
112 reviews
Andrian
31 years of experience
BMW 525i - Check Engine Light is on - Fort Lauderdale, Florida
Highly recommend Adrian for all automotive services. Very professional and extremely knowledgeable about everything related to our car. He explained everything so we knew exactly what was needed and went above and beyond to make the process easy. I would never use another person to work on our cars. EXCELLENT OVERALL!!

Brian

22 years of experience
335 reviews
Brian
22 years of experience
Chevrolet Colorado - Check Engine Light is on - Orange Park, Florida
Brian is a very experienced mechanic. Billing not so sharp. Wrong time (corona-19).to be stiff with adding up, Informing the older customers what to expect? Very sorry to say goodbye to a great mechanic!

Scott

35 years of experience
665 reviews
Scott
35 years of experience
Dodge Grand Caravan - Check Engine Light is on - Phoenix, Arizona
This is the second time I have used his service. All I can say. if he can find my mistakes, he can fix anything. Thanks once again.


More related articles

P0733 OBD-II Trouble Code: Gear 3 Incorrect Ratio
P0733 Code Definition Gear 3 incorrect ratio is the technical definition of the P0733 trouble code What the P0733 code means The...
P0824 OBD-II Trouble Code: Gear Lever Y Position Circuit Intermittent
P0824 means there is an issue with a circuit in the gear level Y position, possibly due to a poorly adjusted or defective sensor.
P2185 OBD-II Trouble Code: Engine Coolant Temperature Sensor 2 Circuit High
P2185 code definition Engine Coolant Temperature Sensor 2 Circuit High What the P2185 code means This code indicates that the sensor is...

Related questions

Is there a way to check my computer to see if it's faulty or not?

Your computer is located inside the car and would need to be tested by scanning the computer to see if it is storing fault codes for an internal problem or an indication to some engine sensors that may have been...

Code p0101

The P0101 trouble code may keep returning if the engine computer does not see the MAF sensor input within a specified range when it is testing the MAF input. The input can be wrong if the engine has another problem...

Engine fault warning lamp flashing

Hey there. This may suggest a short or potentially a bad fuse or relay problem related to your AC. Your car's computer has what is known as a "fail safe" default that is engaged when the computer detects an electrical...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com