P0135 on Ford
O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
P0135 on Ford vehicles indicates o2 sensor heater circuit malfunction (bank 1, sensor 1). Au7o has documented this code across 1 Ford model — most commonly on EcoSport. This code means the heater built into your upstream oxygen (O2) sensor on Bank 1, Sensor 1 — the sensor before the catalytic converter — isn't behaving as the engine computer expects. Modern O2 sensors have an internal heating element so they reach operating temperature quickly and can read the exhaust's oxygen content right after startup. When the computer detects that the heater circuit is open, shorted, or drawing the wrong amount of current, it sets P0135. A cold or slow-to-heat sensor delays accurate fuel mixture readings, which can hurt fuel economy and emissions. Typical repair costs on Ford range from $150 to $800, depending on the specific model and root cause.
Common Causes of P0135
- •Failed O2 sensor heater element (most common)
- •Blown O2 sensor heater fuse
- •Corroded or loose O2 sensor connector
- •Damaged or melted wiring near the exhaust
- •Open or shorted heater control circuit
- •Poor ground or power supply to the sensor
- •Faulty PCM/ECM heater driver (rare)
P0135 on Ford by Model
Ford EcoSport(1 issue)
- Exhaust Flex Pipe Cracking and Exhaust Leak2018-2022
The Ford EcoSport is known for premature exhaust flex pipe failure, where the flexible coupling between the exhaust manifold and the catalytic converter develops cracks and leaks. The flex pipe deteriorates from thermal cycling and vibration, causing a loud exhaust ticking or hissing noise that is most noticeable at startup and during acceleration. The leak can also trigger oxygen sensor codes and cause the check engine light to illuminate. In areas with road salt, corrosion accelerates the failure.
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What does P0135 mean on Ford?▼
P0135 stands for "O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)." This code means the heater built into your upstream oxygen (O2) sensor on Bank 1, Sensor 1 — the sensor before the catalytic converter — isn't behaving as the engine computer expects. Modern O2 sensors have an internal heating element so they reach operating temperature quickly and can read the exhaust's oxygen content right after startup. When the computer detects that the heater circuit is open, shorted, or drawing the wrong amount of current, it sets P0135. A cold or slow-to-heat sensor delays accurate fuel mixture readings, which can hurt fuel economy and emissions. On Ford specifically, this code is documented across 1 model.
What causes P0135 on Ford vehicles?▼
Common causes on Ford: Failed O2 sensor heater element (most common), Blown O2 sensor heater fuse, Corroded or loose O2 sensor connector, Damaged or melted wiring near the exhaust, Open or shorted heater control circuit. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0135 on a Ford?▼
Repair costs on Ford range from $150 to $800, depending on the specific model and root cause.
Which Ford models have P0135 documented?▼
Au7o has documented P0135 on 1 Ford model: EcoSport.