|Trouble Code||Fault Location||Probable Cause|
|P1301||Cylinder Number 1 Random Misfire Detected (ACURA, HONDA)
Misfiring Cylinder 1 (BMW, MINI)
Boost Calibration High (FORD, SAAB)
TDC Sensor Abnormal (HYUNDAI)
Misfire Detected Increased Exhaust Temperature (SUBARU)
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What Does Code P1301 Mean?
SPECIAL NOTE: This code must be treated with some circumspection, because not all online and even print resources list this code and its definition as given below. While this official SAAB resource does list the code and its definition as given below, several, if not most third-party online vendors and resources list this code with definitions for SAAB that range from “Torque Limitation Signal, Long Duration” to “Cylinder 3 – misfire detected”. Therefore, we strongly recommend that you research and determine the exact definition of this code as it applies to your specific SAAB model’s VIN to avoid confusion, misdiagnoses, wasted time, mistakes, and the possible unnecessary replacement of parts and components. END OF SPECIAL NOTE.
OBD II fault code P1301 is a manufacturer-specific trouble code* that is defined by carmaker SAAB as “Boost Calibration High” and is set when the PCM (Powertrain Control Module) detects a condition in which the boost pressure is higher than expected given the current engine load and speed.
* Note that several other manufacturers, including Ford, Citroen, Peugeot, Lincoln, Mercury, Oldsmobile, and possibly others, also assign the definition “Boost Calibration High” to code P1301.
All modern forced induction systems employ several control strategies to manage the boost pressure to higher degrees of accuracy than was possible to do with simple spring-loaded waste gates or dump valves. Foremost among these strategies is the use of a dedicated boost pressure sensor whose function is to provide the PCM with input data on the actual boost pressure at any given point in the engine’s operating range.
These sensors typically convert boost pressure into an electrical signal, which the PCM interprets as the actual boost pressure. However, since the boost pressure fluctuates as a natural consequence of normal engine operation, the PCM uses algorithms that are based on the engine’s speed and calculated load to compare the ideal desired boost pressure to the actual boost pressure as reported by the boost pressure sensor.
The relationship between desired and actual boost pressure is critically important not only for effective boost control, but also to prevent engine damage caused by excessive boost pressures at low engine speeds, or during hard decelerations. As a practical matter, though, boost pressure sensors are calibrated for specific applications, and the PCM depends on this calibration to be correct or within a specified range for that particular application- if it is not, the PCM can’t exert effective control over the turbochargers’ rotational speed through calculated manipulations of the turbocharger’s wastegate.
In practice, the PCM opens and closes the turbocharger’s wastegate to regulate the volume of exhaust gas that drives the turbocharger. Moreover, the PCM is programmed to control the wastegate in such a manner that the maximum drive pressure is always available to eliminate or reduce turbo lag at high engine speeds, which means that the calibration of the boost pressure sensor is critically important for effective boost pressure control.
Therefore, the PCM compares the actual boost pressure to the desired boost pressure continuously, and if it detects that the actual boost pressure (as reported by the boost pressure sensor) approaches or exceeds the desired boost pressure at any point in the engine’s operating range, it will conclude that the boost pressure sensor’s calibration is faulty. If this occurs, the PCM will recognize that it cannot control the boost pressure effectively, and it will set code P1301 and illuminate a warning light as a result.
Where is the P1301 sensor located?
This image shows the location of the boost pressure sensor on a VW Passat application. In this example, the yellow arrow indicates the actual sensor, while the red arrow indicates the sensor’s electrical connector.
Note that the appearance and location of boost control sensors vary greatly between applications, but in all cases, the sensor will be located in the intake system between the turbocharger and the intake manifold. Nonetheless, this part of the intake system can contain multiple sensors, so be sure to consult reliable service information for the affected application to locate and identify the boost pressure sensor correctly to avoid confusion and misdiagnoses.
What are the common causes of code P1301?
Common causes of code P1301 are largely similar across all applications, and could include one or more of the following-
- Defective boost pressure sensor
- Mechanical failure of the turbocharger wastegate, causing it to be stuck in the closed position
- Use of substandard, incorrect, or unsuitable aftermarket boost pressure sensor
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors in the boost control system
- Corrupted software in one or more implicated control modules, including the PCM
- Failed or failing PCM, but note that since this is a rare event, the fault must be sought elsewhere before any control module is reprogrammed or replaced
What are the symptoms of code P1301?
Common symptoms are much the same across all applications, but note that depending on the nature of the problem, the severity of one or more symptoms listed here could vary significantly between applications-
- Stored trouble code and illuminated warning light
- Depending on the nature of the problem, multiple additional codes could be present along with P1301
- Varying degrees of power loss may occur as the result of the PCM inability to control air/fuel ratios effectively
- Intake system ducting could become dislodged or rupture as the result of excessive boost pressure
- The engine may overheat at low engine speeds as the result of excessive boost pressure
- Idling quality may be poor, or the idling speed could exceed specified values
- Severe damage to the turbochargers’ rotating assembly could result
- In rare cases, excessive boost pressure at low engine speeds could cause engine seals and/or gaskets to fail
Lean-running conditions may occur at low engine speeds and loads as a result of the PCM being unable to control the air/fuel ratio effectively at all engine speeds and loads
Other Manufacturer Specific Definitions for P1301Boost Pressure Pressure High (Ford)
Cylinder No. 1 - misfire (Acura)
Heated Catalyst Heater Power Switch Temperature Sensor Electrical Bank 2 (BMW)
Cylinder Number 1 Random Misfire Detected (Honda)
TDC Sensor Abnormal (Hyundai)
Cylinder 1 – misfire detected (Land Rover)
Misfiring Cylinder 1 (Mini)
Cylinder 1 – misfire detected (Saab)
Exhaust gas temperature sensor – misfire/fire due to increased temperature (Subaru)