P0147: O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 3)
Quick Answer
Safe to drive (short-term)
P0147 means the heater circuit in the third oxygen sensor on bank 1, fitted after a second (usually under-floor) catalytic converter, has failed. The heater brings the sensor to operating temperature quickly after a cold start. Without it, the sensor takes several minutes to warm up naturally from exhaust heat. Only a minority of cars have a Sensor 3, so this code applies to specific engine configurations.
- Severity
- Low · Emissions
- Estimated repair cost
- From €1 to €380+, varies by vehicle
€1 or €380, depending on your car.
- Replace O2 sensor heater fuse€1–€3
- Replace Bank 1 Sensor 3€110–€380
A scan shows whether P0147 is really stored on your car, which codes sit next to it and how urgent each one is.
A scan needs a Bluetooth OBD2 adapter (Bluetooth LE on iPhone), about €25-60; the built-in demo runs without one. See which adapter to buy
What does P0147 mean?
P0147 is a emissions-related diagnostic trouble code classified as low severity.
Where it is on the car
- Engine
- Oxygen sensor before the converter (sensor 1)
- Catalytic converter
- Oxygen sensor after the converter (sensor 2, or 3 on some cars)
- Silencer and tailpipe
What are the symptoms of P0147?
- Check engine light illuminated
- Slightly higher cold-start emissions
- Possible failed emissions test
- No noticeable driveability symptoms
- May appear alongside other heater codes (P0141, P0135, P0155, P0161) if a shared fuse is blown
What causes P0147?
Burned-out heater element inside Sensor 3 (normal wear with age and mileage)
: high
Corroded or damaged wiring/connector (road salt, heat exposure)
: medium
Blown O2 sensor heater fuse (affects all sensor heaters at once)
: low
Oil or coolant contamination baking onto the heater element
: low
Faulty ECU heater driver circuit (rare)
: low
Is it safe to drive with P0147?
Generally yes, for short-term driving. Safe to drive. The sensor still works once warmed by exhaust heat. Only affects cold-start emissions and catalyst monitoring during the first few minutes of driving. Fix promptly to keep your emissions system fully functional.
How do you diagnose P0147?
- Confirm the vehicle's exhaust layout. Sensor 3 is only present on cars with a third oxygen sensor after a second catalytic converter
- Check for multiple heater codes (P0141, P0135, P0155, P0161). Multiple codes suggest a shared fuse or wiring issue, not individual sensor failures
- Check the O2 sensor heater fuse in the fuse box. Replace if blown and monitor for recurrence
- Unplug the Sensor 3 connector and measure heater resistance with a multimeter. Healthy: 2-15 ohms. Open circuit (infinite): burned-out heater. Under 1 ohm: short
- Inspect the connector for corrosion, bent pins or water intrusion, and trace wiring for chafing against heat shields
How much does P0147 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace O2 sensor heater fuse | €1–€3 | €0–€0 | €1–€3 | Easy |
| Replace Bank 1 Sensor 3 | €50–€220 | €60–€160 | €110–€380 | Moderate |
| Repair wiring or connector | €5–€30 | €50–€130 | €55–€160 | Moderate |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Related diagnostic codes
Common questions about P0147
- Can I drive with P0147?
- Yes, safely. The heater only affects how quickly the sensor reaches operating temperature. Once warm, it works normally. You will see slightly higher cold-start emissions until the sensor warms naturally from exhaust heat.
- Why does my car have three O2 sensors per bank?
- Some petrol cars built to the strictest emissions standards have a second catalytic converter further down the exhaust, with a third oxygen sensor after it to monitor it. Most passenger cars only have two sensors per bank.
- Can a blown fuse cause P0147?
- Yes. O2 sensor heaters share a fuse on most platforms. If it blows, you will see multiple heater codes at once (P0147 plus P0141, P0135, P0155, P0161). Check the fuse before buying a new sensor.
- How long do O2 sensor heaters last?
- There is no fixed lifespan. Sensor 3 sits in cooler gas further down the exhaust and often outlives the upstream and Sensor 2 heaters, but heavy short-trip driving and oil contamination shorten heater life.