Drive with caution — fix soon.
P0135 means the heater circuit built into the upstream oxygen sensor on Bank 1 isn't drawing the expected current. Modern sensors have a small internal heater so they reach operating temperature quickly; when it fails, the sensor is slow to work at cold start. The fix is often a new sensor, but a blown fuse or bad wiring can also be to blame.
$150 – $450
Varies by vehicle and root cause.
Yes, short-term driving is usually fine, especially once the engine warms up. Fix it soon so cold-start emissions and fuel economy return to normal.
Replacing the oxygen sensor typically costs $150-$450 with labor. If it's just a blown fuse or a wiring repair, it can be considerably cheaper.
It's moderate. The car still drives, but the sensor heater fault affects cold-start performance and will fail an emissions test.
It quickly warms the sensor to operating temperature after start-up so it can read the exhaust accurately right away, rather than waiting for engine heat.