Exhaust Pressure Sensor Circuit Low
The exhaust pressure sensor is reading a voltage lower than expected.
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What it means (plain English)
The exhaust pressure sensor measures the pressure in the exhaust system. If it sees too low of a pressure, it means the readings are faulty or there's a problem with the exhaust system, like a blockage.
What the computer is actually seeing
The engine control module (ECM) expects the exhaust pressure to be within a specific range, typically 0.5 to 4.5 volts at idle. When it sees a voltage below 0.5 volts consistently, it triggers SPN 4350.
What a healthy reading looks like
Expected voltage should be within 0.5 to 4.5 volts. At idle, pressure should be around 1.2 to 2.5 PSI.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors for the exhaust pressure sensor. Check for damage, corrosion, or loose connections.
- 22. Measure the voltage at the exhaust pressure sensor while the engine is running. You should have readings around 1.2 to 2.5 volts.
- 33. If voltage is below 0.5 volts, check wiring continuity to the ECM for shorts or opens.
- 44. If wiring checks out, replace the exhaust pressure sensor and retest.
- 55. If you still see low voltage, investigate potential exhaust system blockages, such as a clogged DPF.
Common causes
- Faulty exhaust pressure sensor
- Open or shorted wiring to the sensor
- Exhaust blockage (like a clogged DPF)
- Corroded connectors at the sensor
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Can I drive with this code active?
It's advised to limit driving, as it could indicate an exhaust blockage affecting performance.
Will the fault come back after resetting?
If the underlying issue isn't fixed, it will likely return once the vehicle is operated normally.
Why is this paired with other SPN codes?
Related codes often arise from the same issue or sensor, amplifying the problem in the exhaust system.
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