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SPN 636 — Crankshaft position sensor

Do not driveTo the nearest safe stop

J1939 code SPN 636. Below — how the fault is worded at the factory by Isuzu, KAMAZ, MAZ, Renault Trucks, SITRAK and YaMZ, and what the second half of the code (FMI) means in the standard.

IsuzuKAMAZMAZRenault TrucksSITRAKYaMZ

Isuzu

FMI 2Cam sensor fault (no signal) (P0340)
FMI 7Cam sensor out of phase (P1345)

KAMAZ

FMI 1Camshaft position sensor. K-line code on KamAZ-5490: MR2 10310.
FMI 3Camshaft position sensor. K-line code on KamAZ-5490: MR2 10309.
FMI 4Camshaft position sensor. K-line code on KamAZ-5490: MR2 10308.
FMI 7Camshaft position sensor. K-line code on KamAZ-5490: MR2 10311.
FMI 8Camshaft position sensor. K-line code on KamAZ-5490: MR2 10312.
FMI 11Camshaft speed sensor: no/invalid signal
FMI 12Camshaft speed sensor: no/invalid signal
FMI 14Camshaft position sensor. K-line code on KamAZ-5490: MR2 10313.

MAZ

FMI 11Camshaft speed sensor circuit fault - Incorrect sensor signal. Blink code: 1-1-3. Power will be reduced. Repair: Check the camshaft speed sensor and its wiring.
FMI 12Camshaft speed sensor circuit fault - No signal from sensor. Blink code: 1-1-3. Power will be reduced. Repair: Check the camshaft speed sensor and its wiring.

Renault Trucks

FMI 2Camshaft speed sensor, signal mismatch. Repair: Check the sensor and the wiring (J 1/18, J 1/19).
FMI 3Pump operating mode sensor: open circuit, short to ground or reversed polarity. Repair: Check the sensor and the engine wiring (A 4, A 31).
FMI 8Camshaft (pump speed) sensor — signal lost, or the injection timing does not match the flywheel. Repair: Check the sensor and the wiring (J 1/18, J 1/19). Check the sensor, the pump and the engine wiring (A 4, A 31). Check the flywheel and pump timing.

SITRAK

FMI 2Crankshaft position sensor signal noise
FMI 4Loss of crankshaft position sensor signal
FMI 8No crankshaft sync signal at engine start

YaMZ

FMI 11Camshaft speed sensor circuit fault (Incorrect sensor signal). Blink code: 1-1-3. Power will be reduced. Repair: Check the camshaft speed sensor and its wiring.
FMI 12Camshaft speed sensor circuit fault (No signal from sensor). Blink code: 1-1-3. Power will be reduced. Repair: Check the camshaft speed sensor and its wiring.

What FMI means in J1939

SPN 636 FMI 1636/1 · 636.1data below normal range (most severe level)
SPN 636 FMI 2636/2 · 636.2data erratic or intermittent
SPN 636 FMI 3636/3 · 636.3voltage above normal or shorted high
SPN 636 FMI 4636/4 · 636.4voltage below normal or shorted to ground
SPN 636 FMI 7636/7 · 636.7mechanical system not responding
SPN 636 FMI 8636/8 · 636.8abnormal frequency or pulse width
SPN 636 FMI 11636/11 · 636.11root cause not known
SPN 636 FMI 12636/12 · 636.12faulty device or component
SPN 636 FMI 14636/14 · 636.14manufacturer-specific instructions

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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