Code Definition

P1137 — Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank 1

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Ford

About P1137

P1137 is a manufacturer-specific powertrain diagnostic trouble code recorded for Ford vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1137 is stored, the module has detected a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1137 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This DTC sets when the Powertrain Control Module (PCM) detects that the downstream Heated Oxygen Sensor (HO2S) on Bank 1 is not switching and consistently indicates a lean condition (low voltage) during closed loop operation. The downstream sensor sits after the catalytic converter and is used mainly to monitor catalyst efficiency, so it normally holds a fairly steady voltage rather than switching like the upstream sensor. A persistently low, lean biased signal points to a fault in the sensor, its wiring, or an exhaust leak drawing air in near the sensor. The driver may notice an illuminated c...

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