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 fuel mixture going into the engine on one side. It's like when you're baking and you accidentally add too much sugar, making the cake taste funny.
The P1191 code indicates an issue with the fuel trim system before the catalytic converter on Bank 2 of the engine. This involves the air-fuel mixture being incorrect, either too rich or too lean.
The P1191 code is triggered when the powertrain control module (PCM) detects that the fuel trim is outside the normal range for Bank 2 before the catalytic converter. This can be due to a variety of reasons, including issues with the oxygen sensor, fuel injectors, or air intake system.
• Check Engine Light is on
• Poor fuel economy
• Rough idling
• Faulty oxygen sensor
• Vacuum leaks
• Fuel injector malfunction
Fuel Trim: Adjustments made by the engine control unit to the air-fuel mixture.
Bank 2: The side of the engine opposite to Bank 1, usually the side without cylinder 1.
• Use an OBD-II scanner to confirm the code
• Inspect oxygen sensors and wiring
• Check for vacuum leaks
• Replace faulty oxygen sensor
• Repair vacuum leaks
• Clean or replace fuel injectors
• OBD-II scanner
• Multimeter
• Vacuum leak detector
$150 - $500
Moderate
• Hyundai Sonata
• Kia Optima
• Ford Explorer
• Regular maintenance of oxygen sensors
• Check for and repair vacuum leaks promptly
• Use high-quality fuel
Engine Performance
• Avoid driving aggressively until the issue is fixed
• Monitor fuel economy for any changes
Check your vehicle's warranty for coverage on emissions-related components.
The P1191 code has been reported more frequently in vehicles with higher mileage and those with less regular maintenance.
Moderate – It is advisable to address this issue soon to avoid potential damage to the catalytic converter.
Ignoring this code can lead to increased emissions, which may not comply with local environmental regulations.
• Engine at operating temperature
• Vehicle at idle
The oxygen sensor related to this code is located on the exhaust manifold of Bank 2, before the catalytic converter.
Q: Can I drive with a P1191 code?
A: It's possible to drive short distances, but prolonged driving can damage the catalytic converter.
Q: Is a P1191 code serious?
A: It's moderately serious and should be addressed to prevent further engine or emissions system damage.
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Fitment Required · Vehicle-fitment part
Relevant when the code or supporting diagnostics point toward upstream or downstream oxygen-sensor faults.
This code family often involves upstream or downstream oxygen-sensor diagnosis.
Verify exact sensor position and vehicle fitment before buying.
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Fitment Required · Vehicle-fitment part
Relevant when catalyst-efficiency or emissions faults persist after proper diagnosis.
Catalyst-efficiency faults sometimes point toward converter problems after proper testing.
Catalytic converters are highly vehicle-specific and should not be purchased by code alone.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.