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.
EGR System: Operation
A backpressure type EGR system is used on 2.2L and 2.5L throttle body fuel injected engines. The backpressure transducer measures the amount of exhaust backpressure and varies the strength of the vacuum signal to the EGR valve. The signal vacuum is bled off into the atmosphere when exhaust backpressure to the EGR drops below a calibrated value.
On California models, an on-board diagnostic system checks the entire EGR system for failures and is activated and monitored only during selected engine/driving conditions to avoid misdiagnosis. When monitored, the EGR solenoid is energized, disabling the EGR. The O2 feedback system is monitored to see if a change occurs. The mixture should go lean and the system will try to richen the mixture. The SMEC monitors EGR system performance and registers a fault code if the system has failed or effectiveness has lessened, and turns on the "CHECK ENGINE" light.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.