P0147: The heater in the oxygen sensor farthest downstream on bank 1 (sensor 3) is not working as the computer expects
O2 sensor heater circuit, bank 1 sensor 3
Severity: Monitor
An oxygen sensor circuit fault mostly affects emissions and fuel economy, and TroubleCodes.net reports little or no drivability change, so book a repair rather than stopping.
P0147 in short
P0147 means the heater circuit of the third oxygen sensor on bank 1 has a fault. A failed heater element means a new sensor; wiring, power or ground faults are the other causes. TroubleCodes.net says the check engine light is usually the only sign, so book a repair.
Oxygen sensors give a useful signal only when hot, so most have an electric heater that the computer switches and monitors.
P0147 sets when the computer finds a fault in the heater control circuit of bank 1 sensor 3. Bank 1 is the side with cylinder 1.
TroubleCodes.net says the only thing most owners notice is the lit check engine light.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Heater element open or high resistance
Common general cause- Why it ranks here
- TroubleCodes.net lists a high resistance or open heater element as a cause; the heater is built into the sensor.
- What would change this
- Heater resistance out of specification on the sensor side raises it.
Cause 2: Fault on the power side of the heater circuit
Possible — needs testing- Why it ranks here
- TroubleCodes.net lists a power-side problem in the heater circuit.
- What would change this
- No supply voltage at the harness connector raises it.
Cause 3: Fault on the ground side of the heater circuit
Possible — needs testing- Why it ranks here
- TroubleCodes.net lists a ground-side problem in the heater circuit.
- What would change this
- Good power but no ground or control at the connector raises it.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all codes and freeze-frame data and note any fuel trim, misfire, exhaust or other oxygen sensor codes stored with P0147
IfFuel trim, misfire or other sensor codes are also stored
It meansRepair those first; they can disturb this sensor.
IfP0147 is the only code
It meansInspect the sensor wiring next.
Step 2: With the exhaust cold, inspect the sensor wiring, connector and related fuses for damage, corrosion and routing near hot parts
Warning:Let the exhaust cool fully before touching the sensor or its wiring. Back-probe connectors gently, never pierce insulation, and follow the wiring diagram for your engine.
IfDamaged wiring, a corroded connector or a blown fuse is found
It meansRepair it.
IfWiring looks good
It meansTest the sensor electrically.
Step 3: Unplug the sensor and test its resistance and the circuit continuity, voltage and ground against the specification for your engine
Warning:Let the exhaust cool fully before touching the sensor or its wiring. Back-probe connectors gently, never pierce insulation, and follow the wiring diagram for your engine.
IfResistance or readings are out of specification, or the removed sensor is contaminated
It meansThe sensor has failed; replace it.
IfSensor and circuit test good
It meansLook at the remaining causes.
Symptoms
- Check engine light with no change in how the car drives
How to fix
Step 1: With the exhaust cold, check the sensor wiring and connector for damage, and check the oxygen sensor heater fuse if your owner's manual lists one.
Parts and cost context
- Oxygen (O2) sensor:Use the correct sensor for that bank and position on your engine; sensors in different positions are often different parts.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
We don't have reviewed vehicle-specific evidence for P0147 yet. The causes and tests above apply across vehicles.
Related codes
No curated relationships for P0147 yet.
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
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