Case IH 3613 – Engine ECU: Too high efficiency of catalyst system

The engine control system monitors the efficiency of the Selective Catalytic Reduction (SCR) catalyst by comparing the readings from the upstream and downstream NOx sensors, as well as exhaust gas temperature sensors. If the system calculates a conversion efficiency that is implausibly high (e.g., the downstream NOx sensor reads zero or lower than physically possible under current engine load), it triggers this code. This almost always indicates a sensor failure (giving a false reading) rather than the catalyst actually performing 'too well.'

• Magnum 180
• Magnum 190
• Magnum 210
• Magnum 225
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• Magnum 370
• Puma 140
• Puma 165
• Puma 185
• Puma 200
• Puma 240
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Quadtrac 350
• Quadtrac 400
• Quadtrac 450
• Quadtrac 500
• Quadtrac 550
• Quadtrac 600
• Optum
• Farmall 110A
• Farmall 120A
• Farmall 130A
• Farmall 140A
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Farmlift
• 521F
• 621F
• 821F
• 921F

1. 1

   Check for accompanying codes related to the NOx sensors (e.g., 3521, 3528, 3529, 3530, 3532, 3533) or exhaust gas temperature sensors. Address specific sensor open/short/timeout errors first.

2. 2

   Connect the CNH Electronic Service Tool (EST) or EASy diagnostic tool to monitor live ppm readings of the upstream and downstream NOx sensors. Look for a downstream sensor stuck at a specific value or reading a constant 0 ppm under load.

3. 3

   Inspect the wiring harnesses and connectors for the downstream NOx sensor and catalyst temperature sensors for chafing, melted wires, or corrosion.

4. 4

   Ensure the Diesel Exhaust Fluid (DEF/AdBlue) is not contaminated and that the dosing valve is not leaking, as erratic dosing can skew efficiency calculations.

1. 1

   Isolate the Faulty Sensor

   Based on the live data, identify if the downstream NOx sensor or the Exhaust Gas Temperature Sensor (EGTS) is providing the implausible reading. In the vast majority of 3613 31F cases, the downstream NOx sensor is the culprit.

2. 2

   Disconnect the Battery

   Turn off the machine's main battery disconnect switch before unplugging emissions sensors to prevent voltage spikes to the ECU.

3. 3

   Remove the Sensor

   Locate the faulty NOx sensor at the outlet of the SCR catalytic converter. Disconnect the 5-pin electrical connector and carefully unscrew the sensor probe from the exhaust pipe. (If replacing the EGTS, locate it in front of the DOC/DPF or SCR).

4. 4

   Install the New Part

   Apply a small amount of anti-seize compound to the threads of the new sensor (if not pre-applied from the factory). Thread it into the exhaust pipe and tighten to the OEM torque specification.

5. 5

   Reconnect Wiring

   Plug in the sensor's electrical connector, ensuring the locking tab clicks into place. Secure the wiring harness away from direct heat sources.

6. 6

   Clear Codes and Test

   Reconnect the battery, connect the CNH EST diagnostic tool, and clear the fault codes. Run the engine up to operating temperature under a load to verify that the NOx conversion efficiency returns to a plausible range and the 3613 code does not return.