Code Details
| Display code | SPN 157 FMI 18 |
|---|---|
| SPN | 157 |
| FMI | 18 |
| OEM code | None listed |
| Manufacturer | Volvo |
| System | Engine �?fuel system |
| Component | High-pressure fuel rail / common rail system |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
The Volvo D13 uses a common rail fuel system requiring very high pressure �?over 1800 bar at full load �?for efficient combustion. When rail pressure drops below the ECM target for the current speed and load, this code sets. Drivers typically notice reduced power under load, smoke, or hard starting. On Volvo VNL trucks with the D13, fuel rail pressure is managed by the high-pressure pump and regulated by the pressure control valve. VCADS Pro monitors fuel rail pressure and can distinguish between below-normal pressure from fuel supply (SPN 94) versus a high-pressure pump efficiency or injector return flow issue. D13 high-pressure fuel pump wear typically shows as progressively worsening below-normal rail pressure under high-load conditions and is confirmed by comparison of commanded versus actual fuel rail pressure in VCADS Pro.
SPN 157 is Injector Metering Rail 1 Pressure in J1939. FMI 18 indicates the measured value is valid but below the normal operating range. On the Volvo D13, the EMS monitors commanded vs. actual rail pressure. Persistent low pressure can trigger protective fuel delivery reductions. VCADS Pro provides commanded and actual rail pressure data and a cylinder cutout function to isolate leaking injectors.
Common Symptoms
- Loss of power under heavy load
- Hard starting or long cranking time
- Black or gray exhaust smoke under acceleration
- Engine misfires or rough idle
- Reduced fuel economy
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- High-pressure fuel pump worn or losing efficiency
- Leaking fuel injectors depressurizing the rail
- Supply pump output too low for high-pressure pump demand
- Primary or secondary fuel filter restricted
- Air leak in the low-pressure fuel supply circuit
First Checks
- Connect Volvo VCADS Pro and monitor actual vs. commanded rail pressure at idle and under load
- Replace primary and secondary fuel filters if restricted
- Test supply pump output pressure at the high-pressure pump inlet
- Inspect low-pressure fuel lines for air leaks
- Use VCADS cylinder cutout to identify leaking injectors
- Monitor fuel rail pressure under load in VCADS Pro — compare commanded vs. actual
- Check fuel filter restriction pressure at the primary and secondary filter stages
Can I Keep Driving?
Power loss is often noticeable under load. If a leaking injector is the cause, continued operation risks cylinder damage. Address this promptly.
Related Codes
Related Lookup Pages
Sources
- Volvo Trucks Tech Info Public Resources Volvo Trucks North America · oem · accessed 2026-06-11 · confidence medium
Source: Volvo Trucks North America, Volvo Trucks Tech Info Public Resources. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - Volvo Trucks / Mack Trucks Technical Support Volvo Trucks North America / Mack Trucks Inc. · oem · accessed 2026-06-10 · confidence medium
Source: Volvo Trucks North America / Mack Trucks Inc., Volvo Trucks / Mack Trucks Technical Support. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium
Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.
Open source
FAQ
How does VCADS Pro identify a leaking injector on the Volvo D13?
VCADS Pro has a cylinder cutout function that temporarily disables fuel delivery to each injector individually. If cutting out a specific cylinder causes rail pressure to rise noticeably, that injector is likely leaking back into the fuel return circuit. Consistent low pressure across all cutouts indicates the high-pressure pump is the more likely cause.
Is the Volvo D13 high-pressure fuel pump the same as in the Mack MP8?
Yes �?the D13 and MP8 share the same fuel system components, including the high-pressure pump. If a pump replacement is needed, the same part number applies to both platforms. Service procedures for the pump are also identical between the two brands.
Can contaminated diesel fuel cause SPN 157 FMI 18 on the Volvo D13?
Yes. Water or debris contamination in diesel fuel can damage the high-pressure pump and injectors, leading to reduced pump efficiency or injector leakback. If contaminated fuel is suspected, drain and flush the fuel system and replace the fuel filters before evaluating pump and injector condition.