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

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P2338 DIAGNOSTIC 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 for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 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$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P2338 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

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

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P2338 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,788

Rating Summary
3,460
163
43
24
98
3,460
163
43
24
98

Rusty

20 years of experience
263 reviews
Rusty
20 years of experience
very knowledgeable about my concerns.
2006 AUDI A4 - CHECK ENGINE LIGHT IS ON - ARLINGTON, TEXAS

Keith

15 years of experience
168 reviews
Keith
15 years of experience
Excellent REAL HONEST guy. I'll have more good things to say after Monday's follow-up I'm sure!
2012 KIA SOUL - CHECK ENGINE LIGHT IS ON - INTERCESSION CITY, FLORIDA

Eric

9 years of experience
222 reviews
Eric
9 years of experience
Was totally comfortable as soon as I shook Eric's hand. Professional, knowledgeable, sharp and crisp. Instant OK? Put my mind at ease with what he was going to do and I left it with him. Had to take wife to Dr appointment. He locked up, cleaned up and shut up everything. Detailed verbal report and of course incredible 8 page detailed analysis.. Totally satisfied so far. Still have some issues with the car that need to be addressed with a subsequent work order. Dave Sutherland
2003 CADILLAC DEVILLE - CHECK ENGINE LIGHT IS ON - CARY, NORTH CAROLINA

Robert

20 years of experience
128 reviews
Robert
20 years of experience
He is the only mechanic I want to work on my car
2009 CHEVROLET IMPALA - CHECK ENGINE LIGHT IS ON - HUMBLE, TEXAS

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...

Related questions

Q: P0741 OBD code

Hello, thanks for writing in about your Volkswagen Passat. Trouble code P0741 indicates: Torque Converter Clutch Circuit Performance or Stuck Off. If you need help with getting this fixed, consider YourMechanic, as one of our mobile technicians can come to...

Q: Check engine light on - 2005 Mercedes-Benz SLK350

Have a mechanic check the code(s), then diagnose the vehicle based on that information. The problem setting the Check Engine Light may be doing other, unseen and expensive damage. A YourMechanic professional can help diagnose this issue by giving your...

Q: Q: EPS light came on

There is a problem with the logic which turns on the EPS dash light for your Forte, which is addressed with Kia Technical Service Bulletin TSB-10044130-2564. Check with your Kia dealer service center for this software update per this TSB....

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.

1-800-701-6230 · hi@yourmechanic.com