SPN 4360: Aftertreatment 1 SCR Conversion Efficiency - ZIPtuning Blog (2024)

SPN 4360 is a fault code related to the Selective Catalyst Reduction (SCR) system, specifically indicating an issue with the SCR inlet temperature. This article provides an in-depth analysis of the code, its implications, and troubleshooting procedures.

Urgency and Drivability

When SPN 4360 appears, it typically doesn't require immediate vehicle shutdown. However, prolonged operation may lead to reduced engine performance and potential damage to the aftertreatment system. It's advisable to schedule a service appointment as soon as possible.

In our workshop, we've noticed that Fault Code SPN 4360 is a recurring issue, particularly with European heavy-duty diesel vehicles. We've seen it most frequently in Volvo, Scania, and Mercedes-Benz trucks, as well as some DAF models. The code often appears alongside other SCR system-related faults, and we've found it's commonly triggered by DEF quality issues or sensor malfunctions. In many cases, simply replacing the SCR inlet temperature sensor resolves the problem, but we've also encountered instances where exhaust leaks or turbocharger issues were the root cause. While we've seen this code in some American and Asian makes, it seems to be more prevalent in European vehicles, possibly due to their more stringent emissions standards and complex SCR systems.

Code Specifics

SPN 4360 is a standardized code used across various heavy-duty diesel engine manufacturers. The specific Failure Mode Identifier (FMI) associated with the SPN can provide additional information:

• FMI 31: SCR Inlet Temperature Low
• FMI 3: SCR Inlet Temperature Sensor Circuit Failed High
• FMI 4: SCR Inlet Temperature Sensor Circuit Failed Low
• FMI 10: SCR Inlet Temperature Sensor – Rationality Error

Components Involved

The primary components associated with this fault code include:

1. SCR system
2. DPF (Diesel Particulate Filter) outlet temperature sensor
3. SCR inlet temperature sensor
4. Exhaust system

Role of Components:

The SCR system reduces NOx emissions by injecting Diesel Exhaust Fluid (DEF) into the exhaust stream. The temperature sensors ensure optimal operating conditions for the SCR catalyst.

Common Causes

1. Degraded, diluted, or incorrect diesel exhaust fluid
2. Malfunctioning temperature sensors
3. Exhaust leaks
4. Oil contamination in the DPF
5. Turbocharger issues

Diagnostic Procedure

1. Connect a diagnostic tool and check for additional fault codes.
2. Inspect the exhaust system for visible damage or leaks.
3. Check the DPF outlet and SCR inlet temperature sensor harnesses for damage.
4. Perform a low-temperature Aftertreatment Device (ATD) check using a diagnostic tool.
5. Monitor temperature readings across DOC inlet, DOC outlet, DPF outlet, and SCR outlet sensors.

Solutions

• Replace faulty temperature sensors
• Repair exhaust leaks
• Address oil contamination issues (e.g., turbocharger repair)
• Ensure proper DEF quality and level

Prevention

1. Regular maintenance of the exhaust and aftertreatment systems
2. Use high-quality DEF
3. Address oil consumption issues promptly

Repair Costs

Costs can vary significantly depending on the root cause:

• Temperature sensor replacement: $200-$500 (€170-€425)
• Exhaust system repair: $500-$2000 (€425-€1700)
• Turbocharger replacement: $2000-$4000 (€1700-€3400)

Parts Costs:

• SCR inlet temperature sensor: $100-$300 (€85-€255)
• DPF outlet temperature sensor: $100-$300 (€85-€255)

SPN 4360 may often occur alongside:

• SPN 4363 (SCR outlet temperature sensor)
• SPN 3246 (Aftertreatment 1 Outlet NOx)
• SPN 3251 (Aftertreatment 1 Outlet Gas Sensor Power Status)

Repair Guide

1. Diagnose the root cause using the steps outlined above.
2. If sensor replacement is necessary:
   a. Locate the faulty sensor (typically near the SCR inlet or DPF outlet).
   b. Disconnect the sensor harness.
   c. Remove the sensor using an appropriate socket (usually 22mm or 7/8").
   d. Install the new sensor, torquing to manufacturer specifications (typically 40-50 Nm or 30-37 ft-lbs).
   e. Reconnect the harness and clear fault codes.
3. For exhaust leaks, inspect and repair as necessary, ensuring proper sealing.
4. Address any oil consumption issues to prevent recurrence.

FAQ: Fault Code SPN 4360

What does SPN 4360 indicate?

SPN 4360 indicates an issue with the Selective Catalyst Reduction (SCR) inlet temperature sensor or circuit.

Is it safe to continue driving with SPN 4360 active?

While immediate shutdown isn’t typically required, prolonged operation may lead to reduced performance and potential damage. It’s best to schedule service soon.

What are the common Failure Mode Identifiers (FMIs) associated with SPN 4360?

Common FMIs include 3 (circuit high), 4 (circuit low), and 16 (temperature high).

What components are involved with SPN 4360?

The SCR system, DPF outlet temperature sensor, SCR inlet temperature sensor, and exhaust system are primarily involved.

What are the main causes of SPN 4360?

Common causes include degraded DEF, faulty temperature sensors, exhaust leaks, oil contamination in the DPF, and turbocharger issues.

How do I diagnose SPN 4360?

Connect a diagnostic tool, check for additional codes, inspect the exhaust system, check sensor harnesses, and monitor temperature readings across various sensors.

Can SPN 4360 be caused by DEF quality issues?

Yes, degraded, diluted, or incorrect diesel exhaust fluid can trigger this code.

What’s the relationship between SPN 4360 and oil consumption?

Excessive oil consumption, often due to turbocharger issues, can lead to oil contamination in the DPF, potentially triggering SPN 4360.

How much does it typically cost to repair SPN 4360?

Costs vary widely, from $200-$500 for sensor replacement to $2000-$4000 for turbocharger replacement.

What other fault codes often appear with SPN 4360?

SPN 4363 (SCR outlet temperature), SPN 3246 (Aftertreatment 1 Outlet NOx), and SPN 3251 (Aftertreatment 1 Outlet Gas Sensor Power Status) are commonly associated.

How can I prevent SPN 4360 from occurring?

Regular maintenance, using high-quality DEF, and promptly addressing oil consumption issues can help prevent this code.

What’s the procedure for replacing the SCR inlet temperature sensor?

Locate the sensor, disconnect the harness, remove the sensor using the appropriate socket, install the new sensor to spec, and reconnect the harness.

Can exhaust leaks cause SPN 4360?

Yes, exhaust leaks can affect SCR inlet temperature readings and trigger this code.

How does the SCR system relate to SPN 4360?

The SCR system reduces NOx emissions, and SPN 4360 indicates an issue with the temperature sensor that ensures optimal SCR catalyst operation.

What’s the difference between SPN 4360 FMI 3 and FMI 4?

FMI 3 indicates the sensor circuit failed high, while FMI 4 indicates it failed low.

Can a faulty turbocharger cause SPN 4360?

Yes, a turbocharger leaking oil can lead to oil contamination in the DPF, potentially triggering SPN 4360.

How does DPF condition affect SPN 4360?

Oil contamination or excessive soot buildup in the DPF can affect exhaust temperatures, potentially triggering SPN 4360.

What voltage should be present at the SCR inlet temperature sensor connector?

Typically, you should see between 2.5 and 3.5 volts across the sensor connector pins.

Can SPN 4360 cause a vehicle derate?

Yes, this fault code can result in engine derate to protect the aftertreatment system.

How long does it typically take to diagnose and repair SPN 4360?

Diagnosis can take 1-2 hours, while repair time varies based on the root cause, ranging from 1-2 hours for sensor replacement to several hours for more complex issues.