A failing radiator anti-tamper sensor or switch that sends erratic or out-of-range data.; Damaged or corroded wiring and connectors between the anti-tamper device and the module that monitors it.; A poor ground connection at the anti-tamper device or at the module, causing reference voltage to drift.; Water intrusion or debris in the connector at the radiator, common after front-end repairs or pressure washing.; A module that has lost its configuration or has an outdated calibration for the anti-tamper input.; Aftermarket replacement radiators or shrouds that lack the correct anti-tamper provision, leaving the circuit open.; A fault in the module itself that processes the anti-tamper signal, though this is the least likely cause.

DTC codes / U05xx · Network communication / U0587

U0587Invalid Data Received From Radiator Anti-Tamper Device

Q: What does code U0587 mean?

Invalid Data Received From Radiator Anti-Tamper Device. U0587 means the module that monitors the radiator anti-tamper device received data it considers invalid, so it cannot trust the signal coming from that component. The anti-tamper device is a sensor or switch that detects whether the radiator or its shroud has been removed or disturbed, and the computer sets this code when the data stream from it is missing, out of range, or contradictory.

U0587 means the module that monitors the radiator anti-tamper device received data it considers invalid, so it cannot trust the signal coming from that component. The anti-tamper device is a sensor or switch that detects whether the radiator or its shroud has been removed or disturbed, and the computer sets this code when the data stream from it is missing, out of range, or contradictory.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Often no symptoms besides the warning light, because the anti-tamper circuit does not affect engine operation.
A message on the dash warning that the radiator or cooling system has been tampered with, if the vehicle displays such alerts.
The cooling fan may run continuously or not at all if the module defaults to a fail-safe strategy.
Remote start or security system functions may be disabled on vehicles that tie the anti-tamper signal into those features.
Intermittent warning light that comes and goes with vibration or temperature changes.
A stored code that returns immediately after clearing even when the vehicle drives normally.

Common causes, most likely first

A failing radiator anti-tamper sensor or switch that sends erratic or out-of-range data.
Damaged or corroded wiring and connectors between the anti-tamper device and the module that monitors it.
A poor ground connection at the anti-tamper device or at the module, causing reference voltage to drift.
Water intrusion or debris in the connector at the radiator, common after front-end repairs or pressure washing.
A module that has lost its configuration or has an outdated calibration for the anti-tamper input.
Aftermarket replacement radiators or shrouds that lack the correct anti-tamper provision, leaving the circuit open.
A fault in the module itself that processes the anti-tamper signal, though this is the least likely cause.

How to diagnose and fix it

Clear the code and road-test the vehicle to confirm whether U0587 returns immediately or only under specific conditions.
Inspect the anti-tamper sensor and its connector at the radiator for physical damage, corrosion, or water intrusion.
Check the sensor's reference voltage and ground at the connector with a multimeter, comparing against the service information for that vehicle.
Perform a wiggle test on the harness while watching live data for the anti-tamper input to catch intermittent wiring faults.
Verify that the installed radiator and shroud are correct for the vehicle and that the anti-tamper device is properly seated.
Check for technical service bulletins or calibration updates for the module that monitors the anti-tamper signal.
If all inputs and wiring test good, substitute a known-good anti-tamper sensor before condemning the module.

Why the anti-tamper code keeps returning

Many technicians replace the anti-tamper sensor first, but a corroded ground or a chafed wire in the front harness is far more common and costs much less to fix.
This code can set after a radiator replacement even when the new radiator is correct, because the anti-tamper device was not transferred or was installed upside down.
A weak battery or low charging voltage can cause the module to misread the anti-tamper signal, so check battery health before chasing the circuit.
U0587 does not mean the engine is overheating or that the radiator is failing; it only reports invalid data from the anti-tamper device, so cooling system repairs are not automatically needed.
On some vehicles the anti-tamper signal is shared with the hood switch or security system, so a fault there can set U0587 without any radiator problem at all.

Can I keep driving with U0587?

You can normally keep driving with U0587 because the anti-tamper circuit does not affect engine safety or cooling performance. Avoid ignoring a simultaneous overheating gauge reading, and have the circuit inspected soon if the warning light is accompanied by fan or security system problems.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.