← code lookup·All fault codes

SPN 938 — Brake Release Modulator Valve Solenoid, Axle #1, Left

Do not driveMinutes

J1939 code SPN 938. Below — how the fault is worded at the factory by Knorr-Bremse EBS and MAN, and what the second half of the code (FMI) means in the standard.

Knorr-Bremse EBS

FMI 5Pressure control valve, exhaust valve, left. Short to Ground
FMI 6Pressure control valve, exhaust valve, left. Short to power supply Ubat
FMI 7Pressure control valve, exhaust valve, left. Short
FMI 10Pressure control valve, exhaust valve, left. Open

MAN

FMI 5Pressure control valve exhaust left - Short to Ground
FMI 6Pressure control valve exhaust left - Short to power supply
FMI 7Pressure control valve exhaust left - Short
FMI 10Pressure control valve exhaust left - Open

What FMI means in J1939

SPN 938 FMI 5938/5 · 938.5current below normal or open circuit
SPN 938 FMI 6938/6 · 938.6current above normal or grounded circuit
SPN 938 FMI 7938/7 · 938.7mechanical system not responding
SPN 938 FMI 10938/10 · 938.10abnormal rate of change

Can I keep driving

Do not drive. Stop as soon as it’s safe to do so — don’t keep going.

What happens if you keep driving

Time you have: Minutes

Part of the brake circuit or ABS/EBS is out of service. The pedal may still feel normal — until the first emergency stop or descent.

Next comes longer stopping distance, a skid on a slick surface, failure on a long downgrade. This is the case where "I will take it slow" does not work.

What to check on the spot

Let the air system build to working pressure and listen for leaks. Don’t drive with faulty brakes.

Nearby: brakes

Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.