Code Definition

P1158 — Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank 2

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

About P1158

P1158 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 P1158 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.

P1158 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

The Powertrain Control Module (PCM) monitors the downstream Heated Oxygen Sensor (HO2S) on Bank 2, mounted after the catalytic converter, to judge catalyst efficiency and on some applications to fine trim fuel. DTC P1158 sets when this downstream Bank 2 sensor fails to switch and stays biased rich during operation, so the PCM cannot confirm normal post catalyst oxygen behavior. Bank 2 is the cylinder bank that does not contain cylinder number 1. A persistent rich indication downstream can come from a genuine rich exhaust reaching the rear sensor, a contaminated sensor, a short to ground in the...

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