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.
DTC 31, EGR Control Pressure/BARO Sensor CKT Low (High Vac): Notes
Manifold Absolute Pressure (MAP) sensor monitors amount of vacuum in EGR circuit and sends a signal back to PCM. Signal is compared to EGR duty cycle calculated by PCM. DTC 31 will set when: actual EGR pressure is less than 15 kPa for 2 seconds. PCM will default to shutting down EGR system.
- This step determines if DTC 31 is result of a hard failure or an intermittent condition.
- Attaching a jumper wire between harness terminals "B" (EGR control pressure/BARO signal circuit) to "C" (5-volt reference circuit), will determine if sensor is at fault, or if there is a problem with PCM or wiring.
- Scan tester may not display 5 volts. It is important that PCM recognized voltage as more than 4 volts, indicating that EGR control pressure/BARO signal circuit and PCM are okay.
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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.