Redundant Air Pressure Sensor Fault
Indicates a fault with the redundant air pressure sensor in the system.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The truck has two air pressure sensors for backup, and one of them is not working right, which can mess with the braking system or air supply for other components.
What the computer is actually seeing
The ECU sees a significant discrepancy between the readings from the primary air pressure sensor and the redundant sensor, often more than 10 psi difference where both should be similar.
What a healthy reading looks like
Normal air pressure readings should be between 100-120 psi when the system is operating correctly after a pressure buildup.
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 at the redundant air pressure sensor for corrosion or damage. Decision point: Are they intact? If not, repair/replace as necessary.
- 22. Check the readings from both the primary and redundant air pressure sensors using a scan tool. Decision point: Is the difference between the two sensors greater than 10 psi? If yes, proceed to the next step.
- 33. Swap the redundant sensor with a known good sensor. Decision point: Does the fault code clear, and do values normalize? If yes, replace the sensor; if no, check the air supply lines for leaks.
Common causes
- Faulty redundant air pressure sensor
- Wiring issues or connectors corroded between the sensor and ECU
- Air leaks or issues in the air supply system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this fault?
It's moderate severity, so you should fix it soon but it's drivable. Just be cautious with braking performance.
Will this code come back after a reset?
If the underlying issue isn't fixed, yes, it will return.
Why does this code pair with SPN 4231?
SPN 4231 is for the primary air pressure sensor; both codes indicate monitored air pressure issues.
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