Temperature Gauge Circuit Malfunction
2003-2003 Mazda MX-5 Miata 1.8L I4
The 2003 Mazda MX-5 Miata is equipped with a 1.8L inline-4 engine. Below you'll find detailed b0404 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.
Description
The engine temperature gauge in the instrument cluster is not functioning or reads incorrectly.
Symptoms
- Temperature gauge stuck at cold
- Gauge stuck at hot
- Temperature gauge erratic
- No temperature warning capability
Common Causes
- Faulty coolant temperature sender for gauge
- Cluster gauge failure
- Wiring issue
- Sender connector corroded
Diagnostic Steps
- Check coolant temp sender resistance
- Test gauge with simulated resistance
- Inspect sender connector
- Compare scan tool temp to gauge reading
Repair Notes
Replace coolant temperature sender for gauge (separate from ECT sensor) or repair cluster.
Related Codes
Other Body Codes
- B0001Driver Frontal Stage 1 Deployment Control
- B0002Driver Frontal Stage 2 Deployment Control
- B0003Passenger Frontal Stage 1 Deployment Control
- B0004Passenger Frontal Stage 2 Deployment Control
- B0005Driver Knee Airbag Deployment Circuit
- B0006Passenger Knee Airbag Deployment Circuit
- B0010Driver Side Airbag Deployment
- B0011Driver Side Airbag Deployment Circuit Open
- B0012Driver Side Airbag Deployment Circuit Short to Ground
- B0013Driver Side Airbag Deployment Circuit Short to Battery
B0404 on Other Vehicles
Common Questions
What does code B0404 mean on a 2003-2003 Mazda MX-5 Miata?
B0404 stands for "Temperature Gauge Circuit Malfunction". The engine temperature gauge in the instrument cluster is not functioning or reads incorrectly.
What are the symptoms of B0404 on a Mazda MX-5 Miata?
Common symptoms of B0404 include: Temperature gauge stuck at cold, Gauge stuck at hot, Temperature gauge erratic, No temperature warning capability.
What causes B0404 on a 2003-2003 Mazda MX-5 Miata?
Common causes of B0404 include: Faulty coolant temperature sender for gauge, Cluster gauge failure, Wiring issue, Sender connector corroded.
Last updated: March 2026