OBD-II Code · Sensors
P0147
O2 Heater (Bank 1 Sensor 3)
Severity
low
Lowest on our scale. Fix it when convenient.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$200–$400
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
B1S3 heater circuit fault.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- CEL after cold start
Likely causes
- Failed heater elementMost common
- Wiring
Read the full diagnostic procedureP0147 sets when the PCM detects a fault in the heater control circuit for Bank 1 Sensor 3 -- either the heater is drawing too much current (shorted e…
P0147 sets when the PCM detects a fault in the heater control circuit for Bank 1 Sensor 3 -- either the heater is drawing too much current (shorted element), no current (open element or broken wire), or the control side cannot pull the circuit to ground. The post-cat heater is a simple ~6-14 ohm resistive element fed 12V on one side and pulsed to ground by the PCM on the other.
Cheapest first
- key-on engine-off, back-probe both heater pins -- one should sit at battery voltage, the other should pulse to near 0V at roughly 1-10 Hz once the PCM commands heater on (about 10-30 seconds after key-on cold).
- If both pins sit at 12V, the PCM driver is not pulling down or the heater is open.
- Pull the connector and ohm the heater element across the two heater pins: 4-15 ohms is healthy on most narrowband sensors at room temperature; open or above 30 ohms means a new sensor; under 2 ohms means a shorted element that will burn the PCM driver if you keep driving.
- Caveat: a fried PCM heater driver (internal MOSFET) will set this code with a perfectly good sensor installed -- if the new sensor sets the same code within 60 seconds and the harness ohms out clean, the driver inside the PCM is dead and replacing sensors becomes an expensive guessing game.
Vehicle-specific patterns2005-2010 Jeep Grand Cherokee WK 4.7L -- post-cat heater fuse (F26 in the underhood TIPM) shares circuit with bank-1 pre-cat and pops on a wet startu…
- 2005-2010Jeep Grand Cherokee WK 4.7L -- post-cat heater fuse (F26 in the underhood TIPM) shares circuit with bank-1 pre-cat and pops on a wet startup, Chrysler TSB 18-040-09 swaps the TIPM.
- 2004-2009Toyota Prius Gen2 1NZ-FXE -- sensor 3 heater element fails internally from extended cat-warmup cycles, no harness fault present, sensor replacement only.
- 2006-2012Ford Fusion 3.0L Duratec -- heater ground splice S402 behind the right strut tower corrodes and adds resistance, sensor heats but slowly enough to trip the monitor.
- 2007-2013GMC Acadia / Buick Enclave 3.6L -- PCM heater driver fails internally, GM bulletin 09-06-04-026 covers PCM replacement after the harness checks clean.
Estimated repair$150 to $720.
Look up another code
P0147 — frequently asked
What does a P0147 code mean?
B1S3 heater circuit fault.
What causes a P0147 code?
Common causes: Failed heater element; Wiring.
What are the symptoms of a P0147 code?
Typical symptoms: CEL after cold start.
Is it safe to drive with a P0147 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $200-$400.
How do I diagnose a P0147 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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