P0030: HO2S Heater Control Circuit (Bank 1 Sensor 1)
The engine computer has found a fault in the circuit that controls the heater for the upstream oxygen sensor on bank 1.
What P0030 means
On many cars the engine computer controls the oxygen sensor heater by switching its ground or power on and off. The P0030 family of codes watches that control circuit. RepairPal explains that P0030 sets when the computer detects that the heater wire for the upstream bank 1 sensor is not operating. It is closely related to P0135, but some makers use P0030 for the control side of the circuit and P0135 for heater performance. RepairPal lists oxygen sensor failure, wiring issues and, less often, a failed computer as the causes, with sensor replacement the most common repair. Because the sensor takes longer to warm up without its heater, fuel control stays in a rough backup mode longer after each start, which increases fuel use and emissions. KBB notes you can still drive but should not ignore it. Shops measure heater resistance, check the fuse and power feed, and test the control wire back to the computer.
Common symptoms
- Check engine light on
- Increased fuel consumption
- Decreased engine performance on some vehicles
- Slower warm up of fuel control
- Often no noticeable change
Most common causes
- Oxygen sensor heater failure
- Open or shorted heater control wiring
- Blown heater fuse
- Corroded connector
- Engine computer heater driver fault
What to check yourself first
Check the oxygen sensor heater fuse. Unplug the bank 1 sensor 1 connector and measure resistance across the heater pins. Look for melted or rubbed wiring along the exhaust.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace oxygen sensor | $440-$523 | RepairPal lists oxygen sensor replacement as the most common repair for P0030. |
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | For wiring or connector problems in the heater circuit. |
| Replace engine control module (ECM/PCM) | $1,122-$1,192 | Only if the computer heater driver is proven faulty, which is uncommon. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
- P0135 O2 Sensor Heater Circuit (Bank 1 Sensor 1)
- P0037 HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
- P0130 O2 Sensor Circuit (Bank 1 Sensor 1)
- P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)