P1157 Engine compartment temperature sensor P1158 Engine compartment temperature sensor

P1157 Engine compartment temperature sensor P1158 Engine compartment temperature sensor

Based on the provided codes, P1157 and P1158 refer to faults in the oxygen sensor and Air/Fuel (A/F) sensor circuits, not an engine compartment temperature sensor

. The exact meaning depends on the make and model of the vehicle. The references to "Engine compartment temperature sensor" in your query likely caused a misinterpretation, as these P11XX codes are manufacturer-specific. 

Here is what these codes typically mean for specific car makes:

P1157 code

• For Honda: This code indicates an issue with the Air/Fuel Ratio (A/F) Sensor 1, which is the upstream or primary oxygen sensor located in the exhaust manifold. The specific fault is a "High Voltage" reading from the sensor.
• For Ford: This code, sometimes seen with P1158, can refer to a lack of switching from the HO2S22 sensor.
• Possible causes for Honda (P1157):
  • A faulty A/F sensor.
  • Damaged or corroded wiring or connectors.
  • Exhaust manifold leaks that cause incorrect sensor readings.
  • A problem with the sensor heater circuit. 

P1158 code

• For Ford: This code, often seen with P1157, can indicate a lack of HO2S22 switch—the sensor on bank 2 is stuck on a rich reading.
• For BMW: This code can point to a fuel trim issue, specifically "Fuel Trim Additive Bank 1 Low".
• Possible causes for Ford (P1158):
  • Faulty oxygen sensor (the HO2S22 sensor).
  • A rich running condition in the engine.
  • Faulty sensor wiring or circuit. 

Common diagnostic steps

Because the codes are manufacturer-specific, a proper diagnosis requires using a specialized scan tool and the factory service manual for your vehicle.

1. Verify the code with a scan tool: Use an OBD-II scanner to confirm the specific P1157 or P1158 code and read any accompanying codes.
2. Inspect the sensor and wiring: Visually inspect the oxygen or A/F sensor and its wiring harness for any signs of damage, corrosion, or frayed wires.
3. Check for exhaust leaks: An exhaust leak near the oxygen sensor can cause incorrect readings. Check for any leaks in the exhaust manifold.
4. Test the sensor: Use a multimeter or a diagnostic tool to test the voltage and resistance of the sensor and its heater circuit.
5. Monitor live data: With an advanced scan tool, monitor the sensor's live data to see if it is switching correctly (for an oxygen sensor) or maintaining the proper voltage (for an A/F sensor). 

Important note

The information on JustAnswer highlights the importance of using high-quality Original Equipment Manufacturer (OEM) sensors for replacement, as cheaper aftermarket sensors can sometimes cause the code to return.