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SPN 171 — Ambient air temperature

Do not driveTo the nearest safe stop

J1939 code SPN 171. Below — how the fault is worded at the factory by Dongfeng, Foton, International, KAMAZ, MAZ, Mercedes-Benz, Renault Trucks, SITRAK, YaMZ and ZF AS-Tronic, and what the second half of the code (FMI) means in the standard.

DongfengFotonInternationalKAMAZMAZMercedes-BenzRenault TrucksSITRAKYaMZZF AS-Tronic

Dongfeng

FMI 2Incorrect ambient temperature signal. Scan tool code: P0071. Effect: Fan and warm-up control may misbehave.
FMI 3Short circuit to power or open circuit of the ambient temperature sensor. Scan tool code: P0073.
FMI 4Short circuit to ground of the ambient temperature sensor. Scan tool code: P0072.

Foton

FMI 3High intake air temperature. Scan tool code: P0073.
FMI 4Air temperature sensor fault. Scan tool code: P0072.

International

FMI 3Ambient Air Temperature — Fault on Analog Input 3 above normal when used for outside temperature
FMI 4Ambient Air Temperature — Fault on Analog Input 3 below normal when used for outside temperature

KAMAZ

FMI 0Ambient air temperature sensor: physical range limit
FMI 1Ambient air temperature sensor: physical range limit
FMI 2Ambient air temperature. K-line code on KamAZ-5490: MR2 13617.
FMI 3Ambient air temperature sensor. K-line code on KamAZ-5490: ADM3 16603.
FMI 4Ambient air temperature sensor. K-line code on KamAZ-5490: ADM3 16604.
FMI 5Ambient air temperature sensor circuit open
FMI 7Ambient air temperature sensor signal out of range
FMI 9Ambient air temperature. K-line code on KamAZ-5490: ADM3 16609.
FMI 12Ambient air temperature sensor
FMI 19Ambient air temperature. K-line code on KamAZ-5490: ADM3 16619.

MAZ

FMI 3Ambient air temperature sensor fault - Voltage above allowed. Blink code: 2-3-5. Repair: Check the ambient air temperature sensor and its wiring.
FMI 4Ambient air temperature sensor fault - Voltage below allowed. Blink code: 2-3-5. Repair: Check the ambient air temperature sensor and its wiring.
FMI 12Ambient air temperature sensor fault - CAN bus signal implausible. Blink code: 2-3-5. Repair: Check the ambient air temperature sensor and its wiring.

Mercedes-Benz

FMI 2Ambient Temperature Sensor Data Erratic
FMI 3Ambient Temperature Sensor shorted to Ubat
FMI 4Ambient Temperature Sensor shorted to GND
FMI 9J1587 Ambient Air Temp Sensor Data Message Stopped Arriving
FMI 14J1587 Ambient Air Temp Sensor Data Not Received

Renault Trucks

FMI 8Erroneous “actual engine torque” signal. Repair: Run the diagnostic check of the EECU. Check the programming. Switch the ignition off, switch it on again and repeat the test. If the fault persists, replace the control unit.

SITRAK

FMI 2Implausible ambient air temperature sensor signal. Scan tool code: P0071. Effect: Fan and warm-up control may misbehave.
FMI 3Ambient air temperature sensor voltage above the upper limit. Scan tool code: P0073.
FMI 4Ambient air temperature sensor voltage below the lower limit. Scan tool code: P0072.
FMI 12Ambient air temperature CAN message error. Scan tool code: P0070. Effect: Loss of communication with the modules, some functions are disabled.
FMI 16Ambient air temperature above the upper limit. Scan tool code: P0070. Effect: Fan and warm-up control may misbehave.
FMI 18Ambient air temperature below the lower limit. Scan tool code: P0070. Effect: Fan and warm-up control may misbehave.
FMI 23Disturbed transmission of the ambient air temperature over CAN. Scan tool code: P0070. Effect: Loss of communication with the modules, some functions are disabled.

YaMZ

FMI 3Ambient air temperature sensor fault (Voltage above allowable limit). Blink code: 2-3-5. Repair: Check the ambient air temperature sensor and its wiring.
FMI 4Ambient air temperature sensor fault (Voltage below allowable limit). Blink code: 2-3-5. Repair: Check the ambient air temperature sensor and its wiring.
FMI 12Ambient air temperature sensor fault (CAN bus signal implausible). Blink code: 2-3-5. Repair: Check the ambient air temperature sensor and its wiring.

ZF AS-Tronic

ZF AS-Tronic uses its own fault numbering: the number in the table below is an internal ZF code, not a J1939 SPN. It matches the title of this page by digit only and means something different.

FMI 8No CAN bus signal: "engine torque".

What FMI means in J1939

SPN 171 FMI 0171/0 · 171.0data above normal range (most severe level)
SPN 171 FMI 1171/1 · 171.1data below normal range (most severe level)
SPN 171 FMI 2171/2 · 171.2data erratic or intermittent
SPN 171 FMI 3171/3 · 171.3voltage above normal or shorted high
SPN 171 FMI 4171/4 · 171.4voltage below normal or shorted to ground
SPN 171 FMI 5171/5 · 171.5current below normal or open circuit
SPN 171 FMI 7171/7 · 171.7mechanical system not responding
SPN 171 FMI 8171/8 · 171.8abnormal frequency or pulse width
SPN 171 FMI 9171/9 · 171.9abnormal update rate
SPN 171 FMI 12171/12 · 171.12faulty device or component
SPN 171 FMI 14171/14 · 171.14manufacturer-specific instructions
SPN 171 FMI 16171/16 · 171.16above normal — moderate severity
SPN 171 FMI 18171/18 · 171.18below normal — moderate severity
SPN 171 FMI 19171/19 · 171.19error in received network data

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: To the nearest safe stop

The code is flagged critical: the manufacturer considers it unsafe to keep driving without checking.

This code alone cannot say what will fail next, so stop at the first safe opportunity and look at it on the spot.

That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.

Nearby: other

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