U059E: Invalid Data Received From NOx Sensor A

What it means

A receiving module detected implausible data from NOx sensor A (smart sensor with own ECU). NOx concentration or pumping current values fail plausibility checks and are rejected; SCR control falls back to substitute values.

At a glance

• Affects emissions; the car can fail an emissions test

How it works

NOx sensor A is an exhaust sensor with its own electronics that measures nitrogen oxides and reports its readings to the emissions system. U059E is set when a receiving module rejects sensor A's reported NOx concentration or related measurement as implausible, so emissions control may use substitute values.

Common causes

Most likely first.

1. Module internal fault or sensor input drift
2. Software version mismatch after replacement
3. Gateway module routing CAN messages incorrectly

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules and save freeze-frame data to identify the receiving module and check for NOx, SCR, exhaust-temperature, and communication codes.
2. Use live data to review NOx sensor A's reported concentration and status alongside exhaust temperature and engine operating conditions for dropouts or implausible readings.
3. Inspect sensor A's connector and harness near its exhaust location for heat damage, corrosion, moisture, or chafing.
4. Check the sensor's power, ground, and communication circuit using the manufacturer's procedure, since this smart sensor has its own electronics.
5. If sensor A or the gateway was recently replaced or updated, confirm the part configuration and software compatibility.
6. If wiring and configuration are correct but sensor A data remains invalid, follow the manufacturer's test procedure to distinguish an internal sensor fault from a problem in the receiving module.

Common fixes

• Repair heat-damaged or chafed wiring and secure sensor A's connector.
• Correct a sensor power, ground, or network connection fault.
• Apply the correct software or configuration after sensor or gateway replacement.
• Replace NOx sensor A if its data remains invalid after circuit and configuration checks.

Can I keep driving?

You can generally drive cautiously if the vehicle runs normally and has no severe warnings, but arrange prompt repair because emissions control may be less effective. Stop if the vehicle loses power or displays a system warning requiring it.