Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the car's computer that controls the fuel injectors on one side of the engine. It can't switch between different fuel modes like it's supposed to.
The Engine Control Module (ECM) is detecting an issue with the circuit responsible for switching fuel modes in the high-pressure injector system on bank 2.
The P31F1 H2 code indicates a malfunction in the circuitry that manages the switchover of fuel modes in the high-pressure injector system for bank 2 of the engine. This could be due to electrical issues, faulty components, or software glitches.
• Check Engine Light is on
• Poor engine performance
• Reduced fuel efficiency
• Faulty high-pressure injector
• Damaged wiring or connectors in the circuit
• ECM software issue
ECM: Engine Control Module
Injector: A device that sprays fuel into the engine's combustion chamber
• Perform a visual inspection of the wiring and connectors.
• Use a multimeter to check for continuity and voltage in the circuit.
• Scan the ECM for any additional codes or software updates.
• Repair or replace damaged wiring or connectors.
• Replace the faulty high-pressure injector.
• Update or reprogram the ECM software.
• OBD-II scanner
• Multimeter
• Screwdriver set
$200 - $800
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regular maintenance checks
• Ensure proper fuel quality
• Avoid harsh driving conditions
Engine Performance
• Have the vehicle inspected by a professional mechanic.
• Avoid driving the vehicle if performance issues are severe.
• Regularly check for software updates for the ECM.
Check with your vehicle manufacturer to see if this issue is covered under warranty.
This code has been associated with vehicles that have advanced fuel injection systems, particularly in models with dual fuel modes.
Moderate – It should be addressed soon to prevent further engine performance issues.
Ignoring this code may lead to increased emissions and potential safety risks due to engine performance issues.
• Engine at operating temperature
• Vehicle in a safe and controlled environment
The high-pressure injector and its associated circuitry are typically located on the engine's bank 2, which is the side of the engine opposite to bank 1.
Q: Can I drive with a P31F1 H2 code?
A: It's not recommended to drive with this code for an extended period as it can lead to poor engine performance and increased fuel consumption.
Q: What happens if I ignore this code?
A: Ignoring this code can result in further damage to the fuel system and decreased engine efficiency.
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.