NOx Sensor Circuit Low Input (Bank 1)
Low voltage detected in the NOx sensor circuit of Bank 1.
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What it means (plain English)
The NOx sensor measures nitrogen oxides in the exhaust. If it shows a low voltage, it means there's not enough electrical signal coming from the sensor to the computer, which can affect emissions control.
What the computer is actually seeing
The engine control module (ECM) monitors the voltage output of the NOx sensor. Normal operation shows around 0.5V to 3V when the system is working properly; low input typically indicates below 0.2V.
What a healthy reading looks like
NOx sensor output voltage should range between 0.5V and 3.0V for normal operation under typical conditions. Below 0.2V triggers this code.
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.
- 1Check the NOx sensor connector for signs of damage or corrosion. Clean or replace if necessary. Decision point: Are the connections secure?
- 2Inspect the wiring between the NOx sensor and the ECM for any signs of wear, fraying, or short circuits. Decision point: Is wiring intact or is there damage?
- 3Use a multimeter to measure the NOx sensor voltage while the engine is running. Expect 0.5V - 3V. Decision point: Is the voltage within normal range?
- 4If voltage is low, replace the NOx sensor. If voltage is normal, check for an ECM issue or software update. Decision point: Did replacing the sensor resolve the code?
Common causes
- Wiring issues (short to ground or open circuit) causing low voltage readings.
- Faulty NOx sensor itself.
- Poor connections at the sensor or ECM.
- Exhaust leaks affecting sensor readings.
- Moisture intrusion in connectors.
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It is moderate severity; you can drive but address it soon to prevent increased emissions and potential damage.
Will this problem come back after repairs?
If the underlying issues like wiring or sensor replacement are thoroughly addressed, it shouldn't return.
Why does this code pair with other NOx-related codes?
Multiple codes indicate potential issues with the NOx sensor system, which can include heating elements, signal problems, or circuit integrity.
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