Fault code P0077 – a step-by-step guide to diagnosing and fixing it

Error code P0077 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected a fault in the intake air temperature sensor circuit, specifically a low voltage at sensor bank 1. This DTC P0077 affects the engine management system and can affect fuel injection and ignition.

What causes can this fault code have?

• Defective intake air temperature sensor (IAT)
• Damaged or interrupted cable to the IAT sensor
• Corroded or loose plug connections
• Short circuit in the sensor cable to ground
• Defective engine control unit (ECU)
• Dirty or clogged air filter
• Faulty ground connection of the sensor

Which symptoms occur in parallel with fault code P0077?

• Loss of engine power: Reduced acceleration and weaker engine power
• Increased fuel consumption: The vehicle consumes more fuel than usual
• Uneven idling: Engine runs unevenly at idle speed
• Starting problems: Difficult cold starting characteristics, especially at low temperatures
• Black smoke: Dark exhaust fumes due to incorrect fuel/air mixture
• Jerking when accelerating: Vehicle does not pull away smoothly

How can the problem with error code P0077 be rectified?

• The repair requires a systematic diagnosis of the intake air temperature components.
• Replace the intake air temperature sensor: Replace the defective IAT sensor with a new original part and install it correctly
• Repair wiring harness: Locate damaged or broken wires to the sensor and repair or replace properly
• Clean plug connections: Thoroughly clean all contacts on the IAT sensor and treat with contact spray
• Change the air filter: Replace the dirty air filter with a new one and check the intake tract for cleanliness
• Check ground connection: Check the ground wires of the sensor and make a new ground connection if necessary
• Test engine control unit: Perform ECU function test and replace or reprogram the control unit if defective