P1478 2014 GMC Sierra Code - Particulate Matter Sensor Temperature Circuit High Voltage
Quick Answer
The Particulate Matter (PM) sensor monitors the amount of the particulates (soot) in the diesel exhaust gas exiting the tailpipe. Common causes include Faulty Exhaust Particulate Matter Sensor, Exhaust Particulate Matter Sensor harness is open or shorted, Exhaust Particulate Matter Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P1478 2014 GMC Sierra indicates Particulate Matter Sensor Temperature Circuit High Voltage.
- Common causes
- Common causes include Faulty Exhaust Particulate Matter Sensor, Exhaust Particulate Matter Sensor harness is open or shorted, Exhaust Particulate Matter Sensor circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P1478 2014 GMC Sierra Description
The operation of the PM Sensor is based on the electrical conductivity characteristic of the diesel particulate. As the exhaust gas flows over the sensing element, soot is absorbed in the combs between the electrodes, eventually creating a conductive path. When the path is formed, it generates a current based on the voltage being applied to the element. The measurement process continues until a preset current value is reached. To avoid misleading readings, the sensor performs a regeneration where the soot is cleaned off by heating up the element before the measurement phase begins. The amount of regenerations is based on vehicle strategy; when the calibrated number of regenerations is reached, the cumulative current readings are used to determine the amount of soot concentration in the exhaust gas which in turn determines the collection efficiency of the Diesel Particulate Filter (DPF).
The Diagnostic Trouble Code (DTC) will be set when the particular matter sensor control unit detects a fault in the particulate matter sensor circuitry.
What are the Possible Causes of the DTC P1478 2014 GMC Sierra?
- Faulty Exhaust Particulate Matter Sensor
- Exhaust Particulate Matter Sensor harness is open or shorted
- Exhaust Particulate Matter Sensor circuit poor electrical connection
How to Fix the DTC P1478 2014 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P1478 2014 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P1478 2014 GMC Sierra Code
What does the OBDII code P1478 mean on a 2014 GMC Sierra?
1. P1478 indicates a high voltage issue in the particulate matter (PM) sensor temperature circuit, which monitors the exhaust system's particulate matter levels and temperature. 2.
What are the symptoms of code P1478 in a 2014 GMC Sierra?
Common symptoms include the check engine light turning on, reduced fuel efficiency, possible limp mode activation, and poor engine performance. 3.
What causes the P1478 code to appear?
Potential causes include a faulty particulate matter sensor, damaged wiring or connectors in the PM sensor circuit, or issues with the vehicle’s PCM (Powertrain Control Module). 4.
Can a dirty particulate matter sensor trigger the P1478 code?
While the code typically points to a high voltage issue, a dirty or clogged PM sensor may also cause sensor malfunction, indirectly contributing to the problem. 5.
How do I diagnose the P1478 code?
Use an OBDII scanner to confirm the code, visually inspect the PM sensor and wiring for damage, and perform voltage and continuity tests on the circuit. 6.
Can I drive my 2014 GMC Sierra with a P1478 code?
It’s not recommended to drive for extended periods with this code, as it may lead to further exhaust system or engine damage and reduced performance. 7.
How is the P1478 code fixed?
Repairs may include replacing the PM sensor, repairing or replacing damaged wiring or connectors, or reprogramming/updating the PCM if necessary. 8.
How much does it cost to repair a P1478 code on a 2014 GMC Sierra?
Repair costs can vary but typically range from $200 to $500, depending on whether the PM sensor or just the wiring needs replacement. 9.
Can a software issue cause the P1478 code?
Yes, outdated or corrupted PCM software can sometimes cause this code to appear, requiring a software update or reprogramming. 10.
Is the P1478 code covered under warranty for a 2014 GMC Sierra?
It depends on your vehicle’s warranty terms, but emissions-related components like the PM sensor may be covered under the federal emissions warranty.
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