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.
Diagnostic Aids
With ignition on and engine off, manifold pressure is equal to atmospheric pressure with signal voltage being high. This information is used by PCM as an indication of vehicle altitude. Comparison of this reading with a known good vehicle with the same sensor is a good way to check the accuracy of a suspect sensor. Readings should be the same plus or minus .4 volt.
DTC 33 will set if an open is present in sensor ground circuit, or if EGR control pressure/BARO signal circuit is shorted to voltage or to 5-volt reference circuit. Ensure electrical connectors remain securely fastened. Refer to EGR CONTROL PRESSURE/BARO SENSOR OUTPUT CHECK chart (see link below) for further diagnosis.
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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.