What Does P0030 Mean?
The ECM has detected a malfunction in the heater control circuit of the upstream heated oxygen sensor (HO2S) on Bank 1, Sensor 1 (pre-catalytic converter). The heater element brings the O2 sensor to operating temperature quickly for accurate readings. Without proper heater function, the sensor takes longer to reach closed-loop operation, causing increased emissions and potentially poor fuel economy during warm-up.
Common Causes
40%
Failed HO2S heater element (internal open or short)
20%
Blown fuse or open relay in the O2 heater power supply circuit
20%
Damaged or corroded wiring/connector in the heater circuit
10%
Poor ground connection for the heater circuit
10%
ECM heater driver circuit failure
Diagnostic Steps
1
Check the O2 heater fuse in the underhood fuse box. If blown, inspect the heater circuit for shorts before replacing the fuse. Also verify the O2 heater relay (if equipped) is clicking and passing voltage.
2
Disconnect the Bank 1 Sensor 1 O2 sensor connector and measure heater element resistance across the heater pins — expect 2–15 ohms (varies by manufacturer; check service data). An OL or near-zero reading indicates a failed heater.
3
With the connector disconnected, verify battery voltage is present on the heater power supply wire with key on. If no voltage, trace the circuit back through the fuse and relay.
4
Check the ECM heater ground control wire for continuity back to the ECM — should be under 1 ohm. Command the heater on with the scan tool and verify the ECM is toggling the ground.
5
Monitor the O2 sensor heater current PID if available. Compare actual current draw to specification (typically 0.5–2.0A). Zero current confirms an open circuit; excessive current suggests a shorted heater element.
Estimated Repair Cost
$80 - $300
Parts + labor, varies by vehicle and location
The ECM has detected a malfunction in the heater control circuit of the upstream heated oxygen sensor (HO2S) on Bank 1, Sensor 1 (pre-catalytic converter). The heater element brings the O2 sensor to operating temperature quickly for accurate readings. Without proper heater function, the sensor takes...
The most common cause of P0030 (Heated Oxygen Sensor (H02S) Heater Control Circuit Bank 1 Sensor 1) is: Failed HO2S heater element (internal open or short)
Typical repair costs for P0030 range from $80 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The O2 sensor will still function once it reaches operating temperature from exhaust heat alone, but warm-up time is extended. Increased cold-start emissions and slightly reduced fuel economy are the primary concerns. Repair before the next emissions inspection.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0030 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System / Emissions
Difficulty
Type
Generic (SAE)
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