HRT stands for Heated Oxygen Sensor (HO2S) Rationality Test. It is a diagnostic test that checks the rationality or plausibility of the heated oxygen sensor (HO2S) readings on your vehicle.
The heated oxygen sensor, also known as the O2 sensor, is part of your vehicle's fuel management and emissions control system. It monitors the oxygen content of the exhaust gases leaving your engine and sends that data to the engine control module (ECM).
The ECM uses the HO2S readings to fine-tune the air-fuel mixture by telling the fuel injectors how much fuel to deliver. This helps optimize combustion efficiency and reduce vehicle emissions.
Why the HRT Test is Needed
Over time, the HO2S can get contaminated or damaged, causing it to send incorrect data to the ECM. This can lead to a rich or lean air-fuel mixture that:
- Reduces fuel economy
- Increases emissions
- Causes drivability issues
To catch HO2S problems, the ECM runs rationality tests on the sensor readings. The
HRT diagnostic specifically focuses on testing the rationality or plausibility of the HO2S voltage and switching activity.
What Happens During the HRT Test
- The test monitors the HO2S voltage readings as they switch between high and low. This switching occurs as the sensor reacts to oxygen content changes in the exhaust.
- It evaluates if the voltage, amplitude, frequency of switching, and response rate are within specification
- It flags any sensor that deviates too far from expected readings
Some common HRT trouble codes include:
- P0130: O2 Sensor Circuit Malfunction
- P0131: O2 Sensor Circuit Low Voltage
- P0132: O2 Sensor Circuit High Voltage
- P0133: O2 Sensor Circuit Slow Response
- P0135: O2 Sensor Heater Circuit Malfunction
HRT Test Failure Causes
An HRT failure can be caused by:
?? Damaged HO2S
?? Contaminated HO2S (oil ash, fuel additives, silicates)
?? Exhaust leaks
?? Catalytic converter failure
?? Engine misfires allowing unburnt fuel into the exhaust
Fixing HRT DTCs
If you get an HRT related trouble code, here are some things to try:
- Inspect HO2S wiring and connectors for damage. Clean connections if dirty
- Monitor live HO2S data on a scanner. Compare to spec and check for unrealistic readings
- Perform an HO2S response test with a scanner
- Replace the oxygen sensor if it is contaminated, damaged, or fails testing
- Diagnose and repair engine misfires or catalytic converter failure
Properly diagnosing and fixing HRT codes is important for engine performance and emissions. If DIY troubleshooting does not resolve the issue, have your vehicle serviced by a professional technician.
At
Hormone Harmony Clinic, our experts use high-quality
diagnostic scan tools to check your vehicle for HRT failures and other issues. We help you accurately pinpoint problems for proper repairs.
Visit us for your next service appointment and benefit from our:
?? Modern diagnostic equipment
?? ASE-certified technicians
?? Vehicle maintenance programs
?? Competitive pricing
Book your appointment online today!
