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PACCAR MX (2004 Emissions) Fault Code: U157B BPV Actuator Temperature – Data Erratic, Intermittent, or Incorrect

Dec 02, 2025

PACCAR MX (2004 Emissions) Fault Code: U157B BPV Actuator Temperature – Data Erratic, Intermittent, or Incorrect

SET CONDITIONS:
The PCI ECU (D420) receives a CAN message from the BPV valve actuator that contains an out-of-range value for the actuator temperature.

DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the ignition is on.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to inactive after the ignition is keyed off for at least 15 seconds and keyed on again, and the fault is no longer detected.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. This DTC can be a result of a BPV valve related P-code. Troubleshooting these P-codes first.
2. E-CAN communication
3. Faulty BPV valve actuator

ADDITIONAL INFORMATION:
1. The actuator of the BPV valve (L096) is a smart actuator that communicates with the PCI ECU via E-CAN. The actuator ECU is controlled by the PCI ECU but has its own diagnostics.

2. The temperature is measured on the of the actuator.

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PACCAR MX (2004 Emissions) Fault Code: U1700 CAN Communication – Message (AT1T1I) Out of Range, DEF Tank Level from Aftertreatment System

Dec 02, 2025

PACCAR MX (2004 Emissions) Fault Code: U1700 CAN Communication – Message (AT1T1I) Out of Range, DEF Tank Level from Aftertreatment System

SET CONDITIONS:
This DTC is set when a CAN message is received correctly, but the content (signal value or status) is out of the expected range.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on or when the engine is running.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. A corrupt or empty CAN message
2. A malfunction in the system from which the message originates

ADDITIONAL INFORMATION:
1. A ‘message out of range’ DTC is activated by the receiving ECU but indicates a malfunction within another system which communicates with this ECU.
2. The cause of the DTC must be sought in the system from which it originates.

Example:
1. [ECU 1] detects an incorrect or missing signal from [sensor A].
2. [ECU 1] sets [DTC 1] (In this specific case, an open circuit DTC).
3. [ECU 1] constantly informs [ECU 2] about the status of [sensor A] via CAN messages.
4. Since the data received from the sensor is not available or not plausible, an ’empty’ CAN message is sent from [ECU 1] to [ECU 2].
5. [ECU 2] interprets the empty message as being out of the expected range and sets the ‘out of range DTC’ [DTC 2].

PACCAR MX (2004 Emissions) Fault Code: U1579 BPV Actuator Position – Data Erratic, Intermittent, or Incorrect

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PACCAR MX (2004 Emissions) Fault Code: U1577 BPV Actuator – CAN, Message Time-Out

PACCAR MX (2004 Emissions) Fault Code: U1575 EGR Valve Module Effort – Data Erratic, Intermittent, or Incorrect

PACCAR MX (2004 Emissions) Fault Code: U1574 EGR Valve Module Temperature – Data Erratic, Intermittent, or Incorrect

PACCAR MX (2004 Emissions) Fault Code: U1573 EGR Valve Module Position – Data Erratic, Intermittent, or Incorrect

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PACCAR MX (2004 Emissions) Fault Code: U1702 CAN Communication – Message (AT1T1I) Out of Range, DEF Tank Heating from Aftertreatment System