P1157 FORD Possible Causes
- Exhaust gas leaks
- Faulty Heated Oxygen Sensor 2 (HO2S2) (downstream), Bank 2
- Heated Oxygen Sensor 2, Bank 2 harness is open or shorted
- Poor electrical connection in Heated Oxygen Sensor 2, Bank 2 circuit
- Inappropriate fuel pressure
- Faulty fuel injectors
How to Fix Code P1157 FORD?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
- Engine light on (or service engine soon warning light)
P1157 FORD Meaning
The Heated Oxygen Sensor 2 (HO2S2) (downstream), after the three-way catalyst (manifold), monitors the oxygen level in the exhaust gases on each bank. For optimal catalyst operation, the air-fuel mixture (air-fuel ratio) must remain close to the ideal stoichiometric ratio. The HO2S2 output voltage changes abruptly near the stoichiometric ratio. The Powertrain Control Module (PCM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S2 generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gases. If oxygen in the exhaust gases increases, the air-fuel ratio becomes lean. The PCM interprets Lean when the HO2S2 voltage is below 0.45 V. If oxygen in the exhaust gases decreases, the air-fuel ratio becomes rich. The PCM interprets Rich when the HO2S2 voltage is above 0.45 V.