P0438 OBD-II Trouble Code: Catalyst Temperature Sensor High (Bank 2)

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

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0438 code

P0438 is a diagnostic trouble code (DTC) for "Catalyst Temperature Sensor High (Bank 2)". 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 P0438 DIAGNOSTIC Get a fair and transparent estimate upfront

P0438 code definition

When your vehicle’s PCM stores trouble code P0438, it means that the catalyst efficiency is below the proper operational threshold for engine bank 2.

What the P0438 code means

Your vehicle’s PCM takes data regarding temperature and exhaust composition from the oxygen sensors in order to determine the required degree of catalyst efficiency. If the proper level is not found, then the PCM stores a P048 code indicating that engine bank 2 is not working properly.

What causes the P0438 code?

Usually, the P0438 code indicates a problem with the catalytic converter. It can also mean that your vehicle has defective oxygen sensors, which is actually the more likely cause. Catalytic converters do not typically wear out, although they can malfunction due to:

  • Improper fuel usage
  • Fuel entering the exhaust system
  • Faulty coolant temperature sensor
  • Bad mass air flow sensor
  • Bad fuel regulator
  • Problems with the fuel injectors
  • Leaky or kinked flex hose
  • Bad spark plug timing

What are the symptoms of the P0438 code?

You might not notice any symptoms – the system might simply store the code, and possibly activate your Check Engine light. On the other hand, if the oxygen sensors are faulty or the catalytic converter is malfunctioning, you might notice a decrease in engine performance, hesitation while accelerating, or stalling.

How does a mechanic diagnose the P0438 code?

Your mechanic will start by using a scanner, volt/ohmmeter, and temperature gun to diagnose the problem. The steps will include:

  • Examining the connectors and wiring, and replacing or repairing anything that is damaged

  • Re-testing the system following repairs

  • If the codes reappear, checking to see if the problem is intermittent (if the problem is determined to be intermittent, then the condition might have to get worse before a proper diagnosis can be made)

  • Comparing the findings with the specifications provided by the vehicle manufacturer

  • Test driving the vehicle, parking it, allowing it to idle, and finding out if the symptoms reappear

  • Taking a reading on the downstream oxygen sensor to see if it fluctuates (this could indicate a bad catalytic converter)

  • Checking the oxygen sensor, fuel trim, fuel mixture and misfire codes before trying to diagnose the catalytic converter codes

Common mistakes when diagnosing the P0438 code

The most common mistake occurs when the mechanic does not properly investigate what caused the failure in the catalytic converter. Often, catalytic converter failure happens when other codes are stored, but not dealt with. Misfires in the engine can also deteriorate the catalytic converter.

Sometimes, too, mechanics are overly eager to replace the oxygen sensor, and may not even verify that it is faulty before doing so. They mean well – they are doing it to avoid the more expensive remedy, which is replacing the catalytic converter. But when they do this, and the problem is actually the catalytic converter, all they are really doing is adding to the expense of repairing the vehicle.

In another effort to save the customer money, mechanics may also go with a rebuilt catalytic converter. Sure, they cost less, but they don’t last as long, and they don’t work as well, as OEM catalytic converters.

How serious is the P0438 code?

If your engine is a bit sluggish and all you’re doing is driving at low speeds, then it probably doesn’t matter much if you don’t get to a mechanic immediately. On the other hand, if you’re stalling out on the highway, that could be dangerous. Depending on where you drive, you might want to get this issue corrected immediately for your safety and that of other motorists, or you might be perfectly fine just having it dealt with when it is convenient for you.

What repairs can fix the P0438 code?

You may need to have your oxygen sensors replaced. Or, you might need a new catalytic converter.

Additional comments for consideration regarding the P0438 code

Exhaust leaks can be a minor annoyance, or they could lead to more costly repairs later on.

Need help with a P808 code?

Exhaust leaks are no problem for YourMechanic. Just give us a call at 1-800-701-6230, or book an appointment using our online form. We will come to your home or office and take care of any maintenance or repair issues for you.

trouble codes
P0438
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0438 code.

SCHEDULE P0438 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

5,606

Rating Summary
5,180
205
50
34
137
5,180
205
50
34
137

James

40 years of experience
34 reviews
James
40 years of experience
Ford F-150 - Check Engine Light is on - Chagrin Falls, Ohio
Jim was great! Arrived on time, quickly diagnosed the problem and recommended further work. Very helpful, I’ll use Jim again and recommend to family and friends.

Roberto

11 years of experience
137 reviews
Roberto
11 years of experience
Nissan Titan - Check Engine Light is on - Spring, Texas
Roberto was very thorough with his explanation of repairs needed. I will contact your mechanic for future repairs.

Matthew

32 years of experience
839 reviews
Matthew
32 years of experience
Kia Optima - Check Engine Light is on - Yorktown, Virginia
Matthew Lerman was God Sent, and thank God for Your Mechanic,, you have my Vote Looking , Looking forward for more Business. Very Honest Guy

Robert

20 years of experience
38 reviews
Robert
20 years of experience
Honda Accord - Check Engine Light is on - Brentwood, California
He came earlier than on time and got the job done faster than I seen anyone else have . Solid honest hard working dude.


More related articles

P0921 OBD-II Trouble Code: Gear Shift Forward Actuator Circuit Range/Performance
P0921 means there is a problem with the gear shift forward actuator circuit, likely due to a faulty actuator or bad wiring.
P0084 OBD-II Trouble Code: Exhaust Valve Control Solenoid Circuit (Bank 2)
P0084 P0084 trouble code definition P0084 is a general code indicating an issue with the exhaust valve control circuit on the bank 2 side of the engine. This code is similar to P0085 and P0086. The engine also has a...
P2443 OBD-II Trouble Code: Secondary Air Injection System Switching Valve Stuck Closed Bank 2
P2443 P2443 code definition Secondary Air Injection System Switching Valve Stuck Closed Bank 2 What the P2443 code means P2443 is an OBD-II generic code for the engine control module (ECM) detecting the exhaust pressure sensor is detecting no exhaust...

Related questions

service engine soon

There is a TECHNICAL SERVICE BULLETIN for the problem and need to reprogram the PCM to a new level. The code is for a cam sensor signal being misread by computer and this TSB needs to be done before replacing...

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...

P0601

This seems to be a common problem on Chrysler Dodge and Jeep vehicles. The P0601 code indicates that your powertrain control module is having a malfunction that has occurred more than six times. It is possible that a battery replacement...

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