P122C Code - Intake Air Flow Valve Control Circuit Shorted
Quick Answer
The intake airflow valve of diesel engines reduces the intake air flow rate in part-load operation so that a higher exhaust gas recirculation rate can be achieved. Common causes include Faulty Throttle Body Assembly, Throttle Body Assembly harness is open or shorted, Throttle Body Assembly 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
- P122C indicates Intake Air Flow Valve Control Circuit Shorted.
- Common causes
- Common causes include Faulty Throttle Body Assembly, Throttle Body Assembly harness is open or shorted, Throttle Body Assembly 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 P122C Description
The Intake airflow valve assembly contains a contactless inductive throttle position sensing element that is managed by a customized integrated circuit. The valve position sensor is mounted within the valve body assembly and is not serviceable. The Engine Control Module (ECM) supplies the valve body with a 5 V reference circuit, a low reference circuit, an H-bridge motor directional control circuit, and an asynchronous signal/serial data circuit. The asynchronous signal means communication is only going from the intake airflow valve to the ECM. The Intake Air Flow Valve cannot receive data from the ECM over the signal/serial data circuit. The valve position sensor provides a signal voltage that changes relative to the valve blade angle. The valve position sensor information is transmitted between the Intake Air Flow Valve and the ECM on the signal/serial data circuit.
The valve may also be used to shut down the engine by closing the intake airflow valve and disabling the fuel injectors if the control module detects the engine speed is beyond the desired control limits. The Diagnostic Trouble Code (DTC) will be set if the ECM detects a high current short circuit on the intake airflow valve control circuit for greater than 0.5 s.
What are the Possible Causes of the DTC P122C?
- Faulty Throttle Body Assembly
- Throttle Body Assembly harness is open or shorted
- Throttle Body Assembly circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P122C?
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 P122C 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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Information for Specific Makes
- P122C BMW — Nitrogen Oxide Sensor Electric Short Circuit
- P122C Buick — Intake Air Flow Valve Control Circuit Shorted
- P122C Cadillac — Intake Air Flow Valve Control Circuit Shorted
- P122C Chevrolet — Intake Air Flow Valve Control Circuit Shorted
- P122C GMC — Intake Air Flow Valve Control Circuit Shorted
- P122C MINI — Nitrogen Oxide Sensor Electric Short Circuit
Frequently Asked Questions about P122C Code
1. What are the common symptoms of OBDII code P122C (Intake Air Flow Valve Control Circuit Shorted)?
The common symptoms include rough idling, stalling, reduced engine performance, and the Check Engine Light coming on.
2. What can cause the Intake Air Flow Valve Control Circuit to short?
The circuit can short due to damaged wiring, a faulty intake air flow valve, or a malfunctioning ECM (Engine Control Module).
3. How can I diagnose the cause of OBDII code P122C?
Diagnosis typically involves checking the wiring harness for damage, testing the intake air flow valve for proper functioning, and using a scan tool to analyze the ECM data.
4. Can I drive my vehicle with OBDII code P122C?
It is not recommended to drive your vehicle with this code as it can lead to further damage and poor engine performance.
5. How is the Intake Air Flow Valve Control Circuit short repaired?
Repair involves identifying and fixing the root cause of the short, such as repairing or replacing damaged wiring, fixing the intake air flow valve, or replacing the ECM if necessary.
6. Will resetting the Check Engine Light resolve OBDII code P122C?
Resetting the light may temporarily turn it off, but the underlying issue causing the code will persist until properly diagnosed and repaired.
7. Are there any preventive measures to avoid OBDII code P122C?
Regular maintenance, such as checking and replacing damaged wiring, inspecting the intake air flow valve, and keeping the ECM in good condition, can help prevent this code.
8. Can a DIY enthusiast repair OBDII code P122C?
Depending on your skill level and access to tools, some simple repairs like checking and replacing damaged wiring can be done by a DIY enthusiast. However, more complex issues may require professional assistance.
9. How long does it typically take to repair OBDII code P122C?
The repair time can vary depending on the exact cause of the code and the availability of parts. It can range from a few hours to a day in more complex cases.
10. What should I do if OBDII code P122C keeps coming back after repair?
If the code keeps reappearing after repair, it indicates that the root cause has not been properly addressed. In such cases, it is recommended to revisit the diagnosis and repair process to ensure all issues are resolved.
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