Cummins fault code 535

What it means

Cummins' description: Engine Fuel Temperature - Data erratic, intermittent or incorrect.

SPN 174 is Engine Fuel Temperature 1. FMI 2 means the signal is jumping around, dropping in and out, or doesn't make sense compared to other readings.

The low-pressure side supplies fuel from the tank to the high-pressure pump. It includes the lift pump, fuel filters, water separator, fuel temperature sensor and water-in-fuel sensor.

What the lamp means

An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.

Common causes

The sensor reading itself is out of range or the condition is real, so look at the system:

• Water in the fuel or a full water separator bowl
• Clogged fuel filter
• Weak or failed lift pump
• Restricted or pinched fuel line
• Low fuel, or fuel gelling in cold weather

What you can check before calling

• Drain the water separator and see if water comes out
• Check when the fuel filters were last changed
• Make sure the tank isn't low, especially on a slope
• In cold weather, think about fuel gelling

Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.

Engines and sources

Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.