P1133 – OBD-II DTC

OBD-II DTC P1133 – Upstream Heated O2 Sensors Swapped

DTC P1133 meaning

DTC P1133 indicates that the upstream heated oxygen sensors (O2 sensors) have been swapped. This code is triggered when the Engine Control Module (ECM) detects a discrepancy in the signals from the O2 sensors that are supposed to monitor the air-fuel mixture in the engine. The upstream O2 sensors are critical for proper fuel management and emissions control.

DTC P1133 symptoms

Common symptoms associated with DTC P1133 may include:

• Check Engine Light (CEL) illuminated
• Poor fuel economy
• Rough engine idle
• Increased emissions
• Failed emissions test

DTC P1133 causes

The causes of DTC P1133 can include:

• Swapped upstream O2 sensors
• Faulty O2 sensors
• Wiring issues or damaged connectors
• Exhaust leaks
• ECM software issues

DTC P1133 seriousness

DTC P1133 is considered a moderate to serious issue. While it may not cause immediate engine failure, it can lead to:

• Increased fuel consumption
• Higher emissions
• Potential damage to the catalytic converter
• Failure to pass emissions testing

How to diagnose DTC P1133

To diagnose DTC P1133, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1133 code.
2. Inspect the wiring and connectors of the upstream O2 sensors for damage or corrosion.
3. Check if the O2 sensors are correctly installed and not swapped.
4. Test the O2 sensors using a multimeter to ensure they are functioning within specifications.
5. Look for any exhaust leaks that may affect sensor readings.
6. Review the ECM for any software updates or issues.

How to fix DTC P1133 step-by-step instructions

To fix DTC P1133, follow these steps:

1. Confirm that the upstream O2 sensors are correctly installed in their respective positions.
2. If sensors are faulty, replace them with new, compatible O2 sensors.
3. Repair or replace any damaged wiring or connectors associated with the O2 sensors.
4. Fix any exhaust leaks that may be present.
5. Clear the DTC using an OBD-II scanner and perform a test drive to ensure the code does not return.

How to erase DTC P1133

To erase DTC P1133, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn the ignition key to the “On” position without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to erase the trouble codes.
5. Disconnect the scanner and start the engine to verify that the code does not reappear.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.