Fault code P1137 – a step-by-step guide to diagnosing and fixing it

Error code P1137 is displayed and the check engine light is on - what does this mean?

The DTC P1137 is triggered by the OBD/EOBD system when a problem is detected with the lambda sensor upstream of the catalytic converter in bank 1. This manufacturer-specific fault code mainly occurs in Ford vehicles and indicates a fuel/air mixture that is too lean or a defective oxygen sensor.

What can cause this fault code?

• Defective lambda sensor upstream of the catalytic converter (bank 1)
• Damaged cable connections to the oxygen sensor
• Corroded or loose plug connections
• Incorrect fuel/air mixture (too lean)
• Defective mass air flow sensor
• Leaks in the intake system
• Clogged or defective fuel filter
• Weak fuel pump
• Defective engine control unit

What symptoms occur in parallel with fault code P1137?

• Poor engine performance: Reduced acceleration and loss of power
• Irregular idling: Engine runs unevenly or stutters at idle speed
• Increased fuel consumption: Noticeably higher consumption than usual
• Starting problems: Difficult cold starting characteristics
• Jerking when driving: Uneven driving behavior, especially at low engine speeds
• Exhaust odor: Unusual smell from the exhaust

How can the problem with error code P1137 be rectified?

• Repairing trouble code P1137 requires a systematic approach to identify the root cause.
• Replace the lambda sensor upstream of the catalytic converter (bank 1) completely and clean the plug connection
• Check all cable connections to the oxygen sensor for damage and repair or replace if necessary
• Clean mass air flow sensor or replace completely if defective
• Check intake system for leaks and replace defective hoses or seals
• Replace fuel filter and measure fuel pressure, replace fuel pump if pressure is low
• Read out engine control unit with diagnostic device and carry out software update or replace ECU if necessary