U059E code meaning
Invalid Data Received From NOx Sensor A
Network system Generic code U05xx codes Check engine light
What U059E means
NOx sensor A usually sits upstream of the SCR catalyst. Its attached electronics turn the probe current into NOx and oxygen readings and broadcast them on CAN. Here those frames still arrive, yet the receiver rejects them. GM's 2025 diesel ECM tables (25OBDG04A/B) count wrong alive rolling counts, protection values or checksums: 8 bad out of 18 samples for most signals, 3 out of 10 for a few, with at least 11 V present for 5 s. It is Type B, so the MIL follows on the second trip. Ford's 2023 diesel summary sets it when the sensor's calibration verification number never reaches the ECU. U029D stands for a silent sensor, U05A1 for the reverse path. Until valid readings return, NOx-based SCR checks and dosing feedback cannot run.
U059E at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of U059E
- Check engine light after the second faulty trip
- SCR and NOx sensor monitors stay incomplete
- Engine usually runs normally
Common causes of U059E
- Most likelySensor control unit of NOx sensor A faulty (heat, moisture, internal error)
- PossibleReplacement sensor of a different part number or software level
- PossibleCorroded connector or damaged CAN/supply wiring at the sensor
- Less likelyEngine controller software needing an update
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Nox sensor a
What each part of U059E means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9E | The exact fault in that area. |
What to do next
- Note U059E and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U059E
What does U059E mean?
U059E means "Invalid Data Received From NOx Sensor A". NOx sensor A usually sits upstream of the SCR catalyst. It is a generic code, so it means the same on every make.
Is it safe to drive with U059E?
Drive gently and only to a workshop. With U059E the car can go into limp mode (reduced power) to protect itself.
Will U059E fail an emissions test?
Yes, it can. U059E is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U059E to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will U059E clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.