Updated Last reviewed September 15, 2026By CarFaultIQ Editorial Team
Verify with official recall databases, service records, a mechanic inspection, and local market data before relying on this summary.
At a glance
Quick diagnostic answer
O2 sensors only read accurately when hot, so they contain heater elements for fast warm-up. The computer monitors heater current; when it's out of range, P0135 sets for bank 1's upstream sensor.
SeverityLowUrgencyUrgency not yet verifiedEvidenceSource notes available
OBD code
P0135
System/category
Sensors & Circuits
Severity
Low
Structured severity term
Urgency
Urgency not yet verified
Can I drive?
Usually OK to drive short-term
Driveable — the engine runs slightly rich until the sensor warms naturally. Fix it to protect economy and the converter.
Repair/cost band
$$ · Moderate
Estimate band only — actual cost varies by region, parts availability and labor rates.
Vehicle applicability
Universal; sensors are wear items and heaters commonly fail with age.
Current applicability note is free text
Computed rule output may be more cautious than stored content and is never used to soften safety-critical risks.
Short answer
P0135 means the heater inside the upstream oxygen sensor isn't working, so the computer runs blind (and rich) longer after every cold start. The usual fix is the sensor itself.
SeverityLowDrive?Usually OK to drive short-termRepairDIY – Moderate
Key takeaways
The usual fix is the sensor itself.
Most common causes: failed heater element inside the sensor (most common) and blown fuse for the heater circuit.
First diagnostic step: check the heater circuit fuse first.
Can I still drive with this?
Usually OK to drive short-term
Driveable — the engine runs slightly rich until the sensor warms naturally. Fix it to protect economy and the converter.
SeverityLow
Low
Diagnostic flow
What it meansO2 sensors only read accurately when hot, so they contain heater elements…
Check this firstCheck the heater circuit fuse first
Likely causeFailed heater element inside the sensor (most common)
Can you drive?Usually OK to drive short-term
P0135 is a generic OBD-II code, which means it carries the same core definition on every make — what differs is which causes are most likely on your engine.
Work the diagnostic steps below in order. They are sequenced from cheapest-and-most-common to most expensive, which is exactly the order a fair shop should follow.
Structured DTC reference
What P0135 means
A fault in the oxygen sensor heater circuit
A trouble code identifies the circuit or monitored condition that failed its test. It does not, by itself, identify the failed part or prove the same cause on every vehicle.
Cause categories to discriminate
Oxygen sensor heater failure
These are structured diagnostic hypotheses, not a parts-replacement list. Vehicle context, symptoms, operating conditions, and test results determine which remain supported.
Severity and drivability
The code alone is not enough to assign one universal severity or “safe to drive” answer. Stop driving for loss of braking or steering, severe overheating, oil-pressure loss, a fuel leak or fire risk, or any rapidly worsening safety symptom.
O2 sensors only read accurately when hot, so they contain heater elements for fast warm-up. The computer monitors heater current; when it's out of range, P0135 sets for bank 1's upstream sensor.
Common symptoms
Check engine light
Slightly worse fuel economy, especially on short trips
Longer rough-ish running after cold starts
Likely causes
Failed heater element inside the sensor (most common)
Blown fuse for the heater circuit
Wiring or connector damage near the exhaust
Rarely, a PCM driver fault
Diagnosis steps
Check the heater circuit fuse first
Measure heater resistance at the sensor against spec
Verify power and ground reach the connector with key on
Replace the sensor if the element is open
Re-check wiring routing — heat-damaged looms re-kill new sensors
What a mechanic should check
Confirm the fuse and wiring before the sensor — a melted connector will take out the replacement too.
Vehicle applicability
Universal; sensors are wear items and heaters commonly fail with age.
Repair actions / cost band
$$ · Moderate
Estimate band only — actual cost varies by region, parts availability and labor rates.
P0135 — vehicles with official records naming this code
P0135 is named in NHTSA-published manufacturer communications or investigations for 29 vehicle families, including:
A code named in a manufacturer communication means the document refers to it for those vehicles. It is not a diagnosis of any car, and it does not mean the code is common on that vehicle.
Frequently asked questions
Can I drive with P0135?
Yes. Expect slightly worse economy until repaired, and don't ignore it forever — rich running shortens converter life.
Should I replace both sensors?
Only the faulty one is required; on high-mileage cars some owners do pairs while access is open. Optional, not mandatory.
Is an aftermarket sensor okay?
Quality matters — cheap universal sensors are a common source of repeat codes. Use a reputable brand or OE.
Honda recalled certain 2020-2024 Ridgeline vehicles because the rearview camera tailgate wire harness can fatigue and break with repeated tailgate use. A…