Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Exhaust Restriction Check: Notes
Exhaust system restriction can be checked by measuring back pressure using the scan tool and pressure tester.
The normal operating temperature of the exhaust system is very high. Therefore, never work around or attempt to service any part of the exhaust system until it is cooled. Special care should be taken when working near the catalytic converter. The temperature of the converter rises to a high level after a short period of engine operation time.
-- Disconnect and remove the upstream (before catalytic converter) oxygen sensor.
-- Install the back pressure test adaptor CH8519.
-- Connect the pressure transducer CH7063 to the back pressure fitting.
-- Following the PEP module instruction manual, connect all required cables to the scan tool and PEP module. Select the available menu options on the scan tool display screen for using the digital pressure gauge function.
-- Apply the park brake and start the engine.
-- With transmission in Park or Neutral, raise engine speed to 2000 RPM. Monitor the pressure readings on the scan tool. Back pressure should not exceed specified limit. Refer to specification in table below EXHAUST BACK PRESSURE LIMIT (MAX) .
-- If pressure exceeds maximum limits, inspect exhaust system for restricted component.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.