Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the way the throttle valve on one side of the engine is working. It's like if one side of a seesaw isn't moving like it should.
The throttle valve controls the amount of air entering the engine. This code indicates that the adaptation process, which ensures the throttle valve operates correctly, has detected a discrepancy on Bank 2 of the engine.
The engine control module (ECM) monitors the throttle valve operation to ensure it opens and closes correctly. If the adaptation values, which are learned positions of the throttle valve, differ from expected values, it triggers this code for Bank 2.
• Check Engine Light illuminated
• Poor engine performance
• Hesitation or stalling
• Faulty throttle body
• Wiring issues in the throttle actuator circuit
• Dirty or clogged throttle body
Throttle Valve: A component that controls the amount of air entering the engine.
Adaptation: The process by which the vehicle's computer learns and adjusts to the throttle valve's position.
• Scan the vehicle for codes and freeze frame data.
• Inspect the throttle body and related wiring for damage.
• Perform a throttle body cleaning and adaptation procedure.
• Replace or repair the throttle body if faulty.
• Fix any wiring issues in the throttle actuator circuit.
• Clean the throttle body and perform an adaptation reset.
• OBD-II scanner
• Multimeter
• Throttle body cleaner
$150 - $500
Moderate
• Audi A4
• Volkswagen Passat
• Porsche Cayenne
• Regular throttle body cleaning
• Routine vehicle maintenance
• Promptly addressing Check Engine Light issues
Sensor Issue
• Avoid driving aggressively until the issue is resolved.
• Get the vehicle inspected by a professional mechanic.
Check with the vehicle manufacturer for warranty coverage on throttle body components.
This code has been known to appear in vehicles with electronic throttle control systems, particularly in models with higher mileage.
Moderate – It's important to address this issue to prevent further engine performance problems.
Driving with a malfunctioning throttle can lead to unsafe driving conditions. Address the issue promptly.
• Engine at operating temperature
• Vehicle in idle or low-load conditions
The throttle body is typically located between the air filter and the intake manifold on the engine.
Q: Can I drive with a P157C code?
A: It's not recommended, as it can lead to poor engine performance and unsafe driving conditions.
Q: How often should I clean the throttle body?
A: It's a good practice to clean the throttle body every 30,000 to 50,000 miles.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.