Yes, you can usually drive in the short term if P0135 is the only issue, but you should investigate and fix it promptly. The long-term impact includes higher emissions, reduced fuel efficiency, and potential damage if left unaddressed.
What P0135 Means
The P0135 diagnostic trouble code indicates a problem with the heater circuit of the oxygen sensor, specifically Bank 1 Sensor 1 (the upstream O2 sensor). The heater helps the sensor reach its operating temperature quickly for accurate readings. When the heater circuit isn’t functioning, the sensor may take longer to warm up, which can affect engine control and emissions.
Can You Drive With P0135?
Most vehicles can be driven for a while after a P0135 fault is detected, especially if the engine is running normally and there are no other drivability problems. Expect potential drop in fuel economy and higher emissions until the sensor warms up, and be aware that some inspections or inspections-based test cycles may fail with the CEL on.
When to be cautious
If you notice severe engine symptoms such as misfires, rough running, hesitation, stalling, or the engine feels markedly off, stop driving and seek professional help. A flashing Check Engine Light usually signals a more serious issue beyond a single sensor heater fault.
Common Causes
Several issues can trigger P0135. The most frequent reasons include the following:
- Faulty O2 sensor (Bank 1 Sensor 1) heater element or sensor itself
- Blown fuse or relay supplying power to the heater circuit
- Poor ground or electrical grounding issues
- ECM/PCM or wiring harness fault
- Accelerated wear from high mileage or exposure to heat
Issues involving the heater circuit can sometimes be resolved without replacing the sensor if the wiring or connections are repaired and the circuit is restored.
Common Symptoms
Along with the diagnostic code, you may notice a few telltale signs that point toward an oxygen sensor heater issue. The list below summarizes typical symptoms you might observe:
- Check Engine Light (MIL) illuminated
- Longer-than-usual engine warm-up times
- Reduced fuel economy or richer/leaner running at startup
- Occasional rough idle or hesitation during acceleration
- O2 sensor readings may be slow to stabilize after startup
Not all vehicles will display all symptoms, and some may run normally aside from the code appearing on the scanner.
Diagnosis and Repair: How It’s Treated
Diagnosing and fixing P0135 typically involves a structured approach. The following steps outline common on-board diagnostics and repair actions a technician might take:
- Verify the code with an OBD-II scanner and check freeze-frame data to understand the conditions under which it was stored.
- Inspect the O2 sensor and its wiring harness for obvious damage, corrosion, or loose connections.
- Check the fuse(s) and relay that supply power to the O2 sensor heater circuit.
- Test the sensor heater circuit resistance with a multimeter, and compare it to the manufacturer’s specifications.
- Inspect grounds and the sensor’s authentication signal to ensure proper electrical grounding.
- If the circuit tests out of spec, replace the faulty O2 sensor. If wiring or connectors are damaged, repair or replace the harness.
- Clear codes and perform a road test to confirm the issue is resolved and that the code does not return.
Time and cost vary by vehicle and parts availability, but the most common fix for P0135 is replacing the upstream O2 sensor or repairing faulty wiring.
Professional Help and When It’s Necessary
If you’re not comfortable performing electrical tests or wiring repairs, or if the code reappears after a repair, seek help from a qualified automotive technician. Persistent emissions-related codes can also affect the vehicle’s inspection status, so addressing the issue before emissions testing is advisable.
Summary
P0135 signals a problem with the heater circuit of Bank 1 Sensor 1, the upstream O2 sensor. While you can usually drive for a short period, the issue can lead to higher emissions and reduced efficiency if left unresolved. Start with a visual inspection of wiring and fuses, test the heater circuit, and replace the sensor or repair wiring as needed. If in doubt, consult a professional to diagnose and implement a complete fix.
Further Reading and Resources
For vehicle-specific guidance, consult your service manual or the manufacturer’s repair database. Always consider local emissions requirements and inspection rules when deciding how long you can drive with a MIL on.
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 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.
How much does it cost to replace a Bank 1 O2 sensor?
The average cost for an O2 sensor replacement is between $362 and $412. This figure includes labor expenses between $63 and $79, while parts range from $300 to $333.
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.