Damaged wiring or poor connector contact in the engine hot lamp control circuit (open, chafed or shorted); Blown bulb, failed LED or fault in the instrument cluster lamp driver; Corroded or loose terminals at the cluster connector or engine control module connector; Blown fuse or loss of ignition feed to the instrument cluster; Fault inside the engine control module output driver; Outdated or faulty module software where a known issue is documented for that model.

P1673

Engine Hot Lamp Control Circuit.

Cadillac
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
6: AreaComputer and output circuits
73: FaultThe specific fault in that area

What it means

P1673 on a Cadillac is a manufacturer-specific code meaning a fault in the Engine Hot Lamp control circuit. The engine control module drives the engine hot warning lamp in the instrument cluster and sets the code when the lamp circuit does not behave as commanded, for example an open circuit, a short to ground or a short to voltage. The exact way the module monitors the circuit can vary by model and year.

Symptoms

Engine hot warning lamp stays on, or never lights
Lamp does not come on briefly at ignition-on during the bulb check
Malfunction indicator lamp or service message may appear
Warning lamp behaviour does not match the real coolant temperature
Other cluster warnings or gauges may act oddly

Possible causes

Damaged wiring or poor connector contact in the engine hot lamp control circuit (open, chafed or shorted)likely
Blown bulb, failed LED or fault in the instrument cluster lamp driverlikely
Corroded or loose terminals at the cluster connector or engine control module connectorpossible
Blown fuse or loss of ignition feed to the instrument clusterpossible
Fault inside the engine control module output driverrare
Outdated or faulty module software where a known issue is documented for that modelrare

How to diagnose

Read all stored codes and freeze frame data, and note whether any cooling system or temperature sensor codes are also present
Check the real coolant temperature with a scan tool and compare it with the gauge and lamp state to confirm the engine is not actually overheating
Watch the lamp at ignition-on to see whether the bulb check works
Check the relevant fuses and the ignition feed to the instrument cluster
Inspect the wiring between the engine control module and the instrument cluster for chafing, water ingress and previous repairs, then check the connectors for corrosion and bent pins
Use the wiring diagram for the specific model to test the lamp control circuit for continuity, short to ground and short to voltage
Use the scan tool's output controls, if supported, to command the lamp on and off and check the response
Check for manufacturer service information or software updates for the model and year

How to fix

Repair or replace damaged wiring and fix any short or open circuit found in the lamp control circuit
Clean or repair corroded terminals and secure loose connectors
Replace the blown fuse after finding and correcting the reason it failed
Replace the failed bulb or repair the instrument cluster if the lamp driver is faulty
Repair or replace the engine control module only after wiring and cluster faults have been ruled out
Apply a manufacturer software update if a documented fault for that model calls for one

Can I keep driving?

Medium severity

The lamp is a warning device, so a fault here means you may not be warned of a genuine overheat. Check the coolant temperature gauge closely and have it repaired soon; if the gauge reads high or the lamp is on with steam or coolant loss, stop driving.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.