OBD-II trouble code
P0043: HO2S Heater Control Circuit Low (Bank 1, Sensor 3)
SAE J2012: heater control circuit low, bank 1 sensor 3. The 2014 Golf book labels the row P0043, bank 1 sensor 3, low, and marks it CBUA only. A low result on a low-side driver still gets a short-to-ground check and a short-to-power check.
Quick facts
- System
- Powertrain
- Category
- Oxygen Sensor
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $300 – $580 (oxygen sensor replacement, parts and labor)
- DIY difficulty
- Intermediate DIY
Browse every code in P0001–P0099, or start from the full code library.
What does P0043 mean?
SAE J2012 APR2002 names P0043 HO2S Heater Control Circuit Low, Bank 1 Sensor 3. Low means the measured characteristic is below the normal range with the circuit connected. Sensor 3 is third in airflow order on the bank that contains cylinder 1.
In the 2014 Volkswagen Golf, GTI, and Golf R Quick Reference Specification Book (NHTSA MC-10122269), engine-code section CBTA and CBUA, the row reads P0043 O2 Sensor Heater Control Circuit Bank 1 Sensor 3 Low (CBUA ONLY). The CBUA-only mark is in the book. A Golf with a different engine code does not inherit that row. The voltage figure printed near that row in the text extract is not quoted, because the columns in that part of the extract do not stay with the codes.
An earlier, tangled extract of the same PDF once attached a "sensor 2" label to a P0043 line. That conflict is why the sensor number used here is the one on the CBUA row that says sensor 3, not the tangled line.
There is no ohm spec in that row. A 2-to-20-ohm heater rule was not found for P0043. The 2005 3.8L L26 calculated-resistance windows are P0053 and P0054, sensors 1 and 2, not sensor 3.
Common causes
- Heater control circuit low on bank 1 sensor 3, the SAE result, measured with the circuit connected
- On a 2014 Golf with engine code CBUA, the sensor 3 low row that book marks CBUA only
- A short to ground in the sensor 3 control wire
- A heater element below the spec this chart prints. That raises current when a ground-side driver switches on. It does not hold the control pin low with the driver off the way a short to ground does
- Sensor 2 tested because the third sensor was never located
- The CBUA row used on an engine code the book does not mark
Symptoms
- Check engine light with P0043
- The third sensor's heater not meeting the low-side threshold this chart uses
- A harness rub at the rear of the vehicle, if that is where this diagram places sensor 3
- P0042 or P0044 absent, which does not cancel the short-to-power check
- No sensor 3 in the parts catalog for this engine, which is a reason to recheck the code
- The code returning after a sensor replacement because the control wire is still grounded
Diagnostic steps
- 1.Confirm a third oxygen sensor exists on bank 1. Then confirm the engine. On a 2014 Golf, the specification book's P0043 row is marked CBUA only.
- 2.Ignition off. Unplug sensor 3. Stands or a lift if it is under the car. Exhaust cool. Inspect the connector for heat damage and water.
- 3.Module disconnected, ignition off: measure the control wire to ground and the control wire for a short to power. Also check the supply for an open. The Golf book does not print the words "short to ground" on the CBUA row that was read. A low code does not skip the short-to-power measurement.
- 4.Measure the sensor's heater only against a spec this procedure prints. No number is supplied here.
- 5.A grounded control wire is a harness repair. A heater that fails its own spec, with a clean wire, is the sensor. Do not replace the converter.
- 6.Clear P0043 and run the heater monitor inside the enable this chart prints.
Repair cost
$300 – $580 (oxygen sensor replacement, parts and labor)
One oxygen sensor, parts and labor, from RepairPal's 3 September 2026 figures. Average $440–$523. Labor $93–$136. Parts $347–$387. The Chevrolet Silverado 1500 example is $306–$407 and the Honda CR-V example is $501–$578. Sensor 3 is not broken out. The printed pair rounds those named ends. A control wire shorted to ground is outside the pair.
Estimate your repair
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Open the Repair Cost Estimator with oxygen sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.