SPN 91 FMI 7 – 2-Channel Accelerator Pedal Idle Not Recognized Fault Code (Symptoms, Causes & Fix)

Mar 15, 2026

The SPN 91 FMI 7 fault code is a diesel engine diagnostic trouble code indicating that the Engine Control Module (ECM) is unable to recognize the idle position of the accelerator pedal. This typically involves the accelerator pedal position sensor, which is crucial for communicating the pedal's position to the ECM.

What SPN 91 FMI 7 Means

When the SPN 91 FMI 7 fault code appears, it signifies an issue with the 2-channel accelerator pedal position sensor. The ECM expects a specific voltage signal from the sensor to confirm the pedal is in the idle position. If this signal is not recognized, the ECM may not correctly interpret the pedal's position, potentially affecting engine performance.

Common Causes of This Fault Code

Failed accelerator pedal position sensor
Wiring harness damage
Connector corrosion or looseness
ECM signal processing issues
Voltage reference faults

Symptoms Drivers May Notice

Drivers may experience symptoms such as erratic engine idling, unexpected acceleration behavior, or a lack of response when pressing the accelerator pedal. These symptoms can vary depending on the severity of the fault and the specific vehicle configuration.

How Technicians Diagnose This Fault

Technicians begin by checking the battery and system voltage to ensure a stable power supply. Next, they verify the power supply and ground circuits to the accelerator pedal position sensor. A visual inspection of the wiring harness is conducted to identify any physical damage or corrosion. Using a multimeter, technicians check the 5-volt reference circuit and measure the sensor's output voltage to confirm it aligns with expected values. Diagnostic software is used to verify ECM data and check for additional fault codes that might indicate broader issues.

Common Misdiagnosis

A common misdiagnosis is replacing the accelerator pedal position sensor without thoroughly checking the wiring integrity. Technicians may also overlook intermittent wiring issues that only manifest under specific conditions, leading to unnecessary part replacements.

Can You Keep Driving?

While it may be possible to continue driving with the SPN 91 FMI 7 fault code active, it is not advisable. The fault can lead to unpredictable engine behavior, potentially causing safety concerns. Additionally, the ECM may initiate an engine derate or protection mode to prevent damage, which can significantly impact vehicle performance.

Mechanic's Diagnostic Tip

When diagnosing SPN 91 FMI 7, always perform a wiggle test on the wiring harness while monitoring the sensor's output with a multimeter. This can help identify intermittent connection issues that are not immediately apparent during a static inspection.

Frequently Asked Questions

Q: Can a software update fix the SPN 91 FMI 7 fault code?
A: In some cases, an ECM software update may resolve signal processing issues, but it's essential to verify all hardware components first.

Q: How often do accelerator pedal position sensors fail?
A: While not the most common failure, these sensors can fail due to wear or exposure to harsh conditions, especially in high-mileage vehicles.

Q: Is it necessary to replace the entire pedal assembly?
A: Not always. If the fault is isolated to the sensor or wiring, replacing the entire pedal assembly may not be necessary.