P037B

Symptoms

• The pre-heating lamp is constantly on or does not go out
• Check Engine Light Is On
• Possible difficulties starting a diesel engine in the cold
• Other symptoms associated with glow plugs, if they are also faulty

Causes

• Short circuit of the lamp control circuit to +12V
• Malfunction of the glow plug control unit
• Damage to instrument panel harness wiring
• Warm-up lamp relay malfunction
• ECU malfunction (rare)

How to Fix

1. Read codes, check for associated glow plug codes (P0380–P0385)
2. Check the voltage at the lamp control circuit on the dashboard
3. Inspect the glow plug control unit connector
4. Check the wiring from the computer to the short-circuit lamp to the positive bus
5. Check the warm-up lamp control relay
6. If necessary, replace the spark plug control unit or eliminate the short circuit

Related codes

Error P037B by Vehicle Brand