Aftertreatment Temperature Sensor 1
Indicates an issue with the aftertreatment system temperature sensor 1.
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 computer uses this sensor to monitor the temperature of the exhaust aftertreatment system, which helps manage emissions. If the sensor fails, the system doesn’t know if it’s getting too hot or too cold, affecting performance and emissions control.
What the computer is actually seeing
The ECM (Engine Control Module) looks for a temperature signal that should ideally be between 150°F (65°C) and 180°F (82°C) when the engine is at operating temperature. If the value is out of range (below 0°F or above 400°F), it triggers the fault code.
What a healthy reading looks like
The expected output from the sensor should range from 0.5V to 4.5V, correlating to temperatures between -40°F and 250°F.
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.
- 1Inspect the sensor wiring for damage or disconnection and repair if necessary. Decision point: Is the wiring intact?
- 2Check the connector for corrosion or looseness; clean or tighten as needed. Decision point: Are connections secure?
- 3Measure the voltage at the sensor connector while the engine is at operating temperature. Expected: 0.5V to 4.5V. Decision point: Is the voltage within range?
- 4If voltage is out of range, replace the temperature sensor. Decision point: Did replacing fix the issue?
Common causes
- Open circuit in the sensor wiring
- Failed temperature sensor
- Poor connector connection
- Exhaust leaks affecting sensor performance
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderately severe; you might experience reduced emissions control and potential exhaust issues but may not see immediate drivability concerns.
Will this code return after repair?
If the wiring and connections are good, and you replace the faulty sensor, it should not return. Monitor it after the repair.
Why might this code appear with other SPN codes?
This code often pairs with exhaust system faults or other sensor failures indicating broader aftertreatment issues.
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