In most cases you can drive short distances, but it’s not a fix. A P0135 fault indicates the heater circuit for the upstream oxygen sensor (Bank 1 Sensor 1) isn’t working properly, which can affect cold-start performance, fuel economy, and emissions. Have the issue diagnosed and repaired promptly to avoid longer-term damage or failing an emissions test.
What P0135 Means
P0135 is the diagnostic trouble code for O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1). The upstream O2 sensor measures exhaust gases to help the engine manage the air-fuel ratio. The heater heats the sensor to its operating temperature quickly, ensuring accurate readings. When the heater circuit fails, the sensor takes longer to reach temperature, causing the engine to rely on a less accurate reading—often triggering the check engine light.
Where the sensor sits and why it matters
Bank 1 Sensor 1 sits before the catalytic converter on the bank that contains the number one cylinder. If it isn't heating properly, the PCM may stay in open-loop longer after startup, which can degrade fuel economy and increase emissions until the sensor warms up or is replaced.
Can You Drive with P0135?
Short-term driving considerations
Yes, you can usually drive for short trips, but you should avoid long highway drives or heavy acceleration if the light is on. Expect possible rough idling, hesitation, or richer fuel mixture when starting from cold, and be aware that emissions sensors may be reporting inaccurate data until the issue is fixed.
Additionally, if the engine runs poorly, your vehicle may experience increased exhaust temperatures or stress on the catalytic converter. If you notice significant loss of power or the engine stalls, pull over safely and seek assistance.
What to Do Now
Below are common causes and practical steps to diagnose and address P0135. Before attempting repairs, ensure your vehicle is safely parked and the battery is disconnected if you plan to work on wiring.
Common causes of P0135 include electrical faults and sensor issues that affect the O2 heater circuit.
- Blown fuse or relay powering the O2 heater circuit
- Damaged or frayed wiring in the heater circuit
- Faulty oxygen sensor heater element
- Loose, corroded, or damaged sensor connectors
- ECU/PCM fault or software issue
The listed items are the typical starting points for diagnosing P0135. A professional scan can confirm whether the heater current is reaching the sensor and whether the problem lies in the wiring, fuse, or the sensor itself.
Immediate Steps if P0135 Is Detected
Take these steps to minimize risk and prepare for a proper repair job.
- Check dashboard lights: if the Check Engine Light is on, note any accompanying symptoms such as rough idle or poor acceleration.
- Inspect the O2 sensor wiring harness and connectors for visible damage or corrosion.
- Check the associated fuse/relay for the O2 heater circuit and replace if blown, using the vehicle's fuse diagram.
- Use a scan tool to monitor live data and verify whether the O2 heater is drawing current and the sensor is warming up in a reasonable time.
- If the sensor is suspect, plan for replacement and have a technician inspect the wiring harness for shorts or grounding issues.
Concluding: In many cases, the fix is replacing the upstream O2 sensor or repairing the heater circuit wiring. If there are additional codes or catalytic converter concerns, the scope may expand.
Repair Options and Cost Expectations
Possible repairs vary by cause and vehicle. The price range may include parts and labor, and costs differ by location and vehicle model.
- Replace Bank 1 Sensor 1 O2 sensor (upstream) if the heater element is faulty
- Repair or replace damaged wiring or connectors in the heater circuit
- Replace blown fuse or relay powering the heater circuit
- Update or reprogram ECU if software-related fault
- Inspect catalytic converter for potential damage if the fault persisted for a long time with incorrect readings
On average, an upstream O2 sensor replacement can cost between $100 and $300 including labor, depending on the car. Wiring repairs may be less or more expensive depending on access and extent of damage.
Diagnosis and Safety Considerations
Mechanics typically verify P0135 with a diagnostic scan to confirm heater current, inspect the wiring harness, test resistance of the heater element, and assess sensor data. While the fault itself isn’t an immediate safety hazard, ignoring it can lead to higher emissions, reduced fuel economy, and potential damage to the catalytic converter. If you notice misfires, stalling, or significant loss of power, seek assistance promptly.
Summary
P0135 refers to a malfunction in the O2 sensor heater circuit for Bank 1 Sensor 1, the upstream sensor. You can typically drive for short periods, but the issue should be diagnosed and repaired promptly to restore accurate emissions readings, optimize fuel economy, and protect the catalytic converter. It most often stems from a blown fuse/relay, damaged wiring, or a faulty sensor; replacement or wiring repair usually resolves the code. Always consult a qualified technician for an accurate diagnosis and repair plan.
How much does it cost to fix P0135?
Fixing P0135 is usually an inexpensive repair. Depending on your vehicle, a new oxygen sensor costs between $20 and $200. Labor can add another $50 to $200 if you go to a mechanic.
Is it safe to drive with a P0135 code?
Yes, you can drive with the P0135 code, but it's best to address this issue promptly. The malfunction may cause increased fuel consumption, higher emissions, and, if left unresolved, can lead to damage to other emission-related components.
How long can I drive with a bad oxygen sensor?
If you keep driving it, even for a week, you're likely to damage the engine further. You can drive without an o2 sensor with no MAJOR problems outside of terrible fuel economy. That said, as was already posted, it could be something other than an o2 sensor.
Will the P0135 code go away on its own?
Will P0135 go away on its own? Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.