P0043 OBD-II Trouble Code: HO2S Heater Control Circuit Low (Bank 1 Sensor 3)

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

SCHEDULE P0043 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0043 code

P0043 is a diagnostic trouble code (DTC) for "HO2S Heater Control Circuit Low (Bank 1 Sensor 3)". 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 P0043 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light logo

P0043 code definition

P0043 stands for low circuit voltage for the heated oxygen sensor bank 1 sensor 3. This code can be seen with P0044 and P0042.

What the P0043 code means

The definition of P0043 is low voltage for the heater control circuit. P0043 indicates that the car’s ECU has detected lower than expected voltage and has triggered a warning light.

What causes the P0043 code?

P0043 may have a few typical causes:

  • Bank 1 sensor 3 has failed
  • Open or shorted wiring for bank 1 sensor 3
  • Poor electrical connection or high resistance
  • Internal ECU issues

What are the symptoms of the P0043 code?

The vehicle’s engine control unit (ECU) detects lower than specified voltage from bank 1 sensor 3’s heater circuit. This triggers the Check Engine Light to be illuminated on the dash. When the heater control circuit malfunctions, it causes readings to not be accurate for bank 1 sensor 3. In rare cases, the vehicle may experience rough running and poor fuel economy.

How does a mechanic diagnose the P0043 code?

As with most DTC’s, step-by-step diagnostics are required to rule out simple issues before looking at more complex ones. Repair steps are as follows:

  • A scan tool is installed into vehicles OBD-II port to check if P0043 is present

  • Freeze frame data is observed so conditions for the code being triggered can be recreated

  • The code is cleared and a test drive is performed under the same conditions as the freeze frame data indicated.

  • If the Check Engine Light returns upon test, then the code is confirmed.

  • The technician performs a visual inspection of wiring and bank 1 sensor 3 for any damage, breaks, or shorted wiring.

  • Bank 1 sensor 3 voltage is checked to make sure it is not excessively low.

  • If low voltage is confirmed, bank 1 sensor 3 is faulty

  • If low voltage was not present, a diagnostic of the ECU will be performed, this test is manufacture and vehicle-make specific.

Common mistakes when diagnosing the P0043 code

P0043 is an uncommon code. Following all steps and not skipping anything is important so nothing is overlooked. Oxygen sensors should not be cleaned, and if faulty, should be replaced. Always confirm low voltage for oxygen sensor bank 1 sensor 3 before any replacement is performed.

How serious is the P0043 code?

P0043 is generally not a serious code as it usually does not cause any symptoms other than the Check Engine Light. With poor fuel economy and the vehicle running roughly, it is recommended to have this code looked at by a qualified technician as soon as possible to ensure safe operation of the vehicle.

What repairs can fix the P0043 code?

The most common repairs are as follows:

Additional comments for consideration regarding the P0043 code

Though this code is more uncommon, it does occur periodically. Following all steps and not jumping to conclusions before checking is important to make fixing this code simple. Refer to manufacture diagrams for the wiring and sensor locations to aid in diagnostics.

Need help with a P0043 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.

Check Engine Light
trouble codes
P0043

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

SCHEDULE P0043 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

3,526

Rating Summary
3,215
155
41
23
92
3,215
155
41
23
92

Trung

9 years of experience
397 reviews
Trung
9 years of experience
A very nice guy! Quick, efficient and very honest. I now have an appointment scheduled this Saturday and only trust Trung to work on my car! Thanks again and I'll see you soon!
2012 NISSAN VERSA - CHECK ENGINE LIGHT IS ON - SAN JOSE, CALIFORNIA

Chris

19 years of experience
1240 reviews
Chris
19 years of experience
Very good mechanic. Can't go wrong with Chris. He is extremely knowledgeable in interpreting OBD2 scanning codes. I will definitely use him again.
2008 BMW 328I - CHECK ENGINE LIGHT IS ON - COSTA MESA, CALIFORNIA

Martin

20 years of experience
16 reviews
Martin
20 years of experience
Excellent. Very professional and on time.
2002 DODGE RAM 1500 - CHECK ENGINE LIGHT IS ON - HOUSTON, TEXAS

Brett

7 years of experience
167 reviews
Brett
7 years of experience
Brett was thorough and told me exactly what was wrong without trying to upsell me. Very friendly and easy to talk to
2004 CHEVROLET SILVERADO 1500 - CHECK ENGINE LIGHT IS ON - AUSTIN, TEXAS

More related articles

Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
P2422 OBD-II Trouble Code: Evaporative Emissions Control System (EVAP) Vent Valve Stuck Closed
Diagnostic Trouble Code (DTC): P2422 P2422 code definition Evaporative Emissions Control System (EVAP)...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...

Related questions

Q: I have a 2002 Toyota Corolla and I'm having hesitation issues coming from a stop. I have tried everything to try and fix it. I hav

Claimed by Kevin Gainer

Q: P0174, P1004 codes

Hello. From what you describe it would appear that your vehicle is experiencing some sort of fuel or engine performance issues. Code P0174 is for an lean condition in engine bank 2. This can be caused by many things, however...

Q: Two mechanics have not been able to repair misfire.

Hi there. Check the intake for a possible vacuum leak around the cylinder 4. If there is no vacuum leak around the cylinder number 4, then there could be a burned valve. Check the compression on all of the cylinders...

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