P122B Code - Intake Air Flow Valve Control Supply Voltage Circuit
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
- P122B indicates Intake Air Flow Valve Control Supply Voltage Circuit.
- 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 P122B 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 an open circuit on the intake airflow valve control circuit.
What are the Possible Causes of the DTC P122B?
- 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 P122B?
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 P122B 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.
Need more information about the P122B code?
Need more information on how to fix the P122B code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P122B code diagnosed by a professional: Find a repair shop in your area
Information for Specific Makes
- P122B Buick — Intake Air Flow Valve Control Supply Voltage Circuit
- P122B Cadillac — Intake Air Flow Valve Control Supply Voltage Circuit
- P122B Chevrolet — Intake Air Flow Valve Control Supply Voltage Circuit
- P122B GMC — Intake Air Flow Valve Control Supply Voltage Circuit
Frequently Asked Questions about P122B Code
1. What are common symptoms of OBDII code P122B?
- Common symptoms include poor engine performance, rough idle, stalling, and a decrease in fuel efficiency.
2. What can cause OBDII code P122B to trigger?
- The code P122B is typically triggered by issues with the intake air flow valve control supply voltage circuit, such as a faulty valve or wiring issues.
3. How can I diagnose the cause of OBDII code P122B?
- Diagnosis involves checking the intake air flow valve, inspecting the wiring for any damage or loose connections, and testing the voltage supply to the valve.
4. Can a dirty air filter cause OBDII code P122B?
- While a dirty air filter can impact engine performance, it is not a direct cause of code P122B. However, it is recommended to ensure the air filter is clean and not contributing to any airflow restrictions.
5. What are some repair tips for fixing OBDII code P122B?
- Repair tips may include replacing the intake air flow valve, repairing any damaged wiring, ensuring proper voltage supply, and clearing the code to see if it reoccurs.
6. Is it safe to continue driving with OBDII code P122B present?
- It is not recommended to continue driving with the code present, as it can lead to further engine issues and potential damage if left unresolved.
7. Can I reset OBDII code P122B without fixing the underlying issue?
- While you can clear the code using an OBDII scanner, it is important to address the underlying issue causing the code to prevent it from reoccurring.
8. How much does it typically cost to repair OBDII code P122B?
- The cost of repairing OBDII code P122B can vary depending on the cause of the issue, but it may involve parts and labor expenses ranging from $100 to $500 or more.
9. Will OBDII code P122B cause my vehicle to fail an emissions test?
- Yes, OBDII code P122B can cause your vehicle to fail an emissions test, as it indicates a problem with the intake air flow valve control supply voltage circuit.
10. Can a DIY enthusiast repair OBDII code P122B, or should it be done by a professional mechanic?
- Depending on your knowledge and experience with automotive repairs, you may be able to address OBDII code P122B as a DIY project. However, if you are unsure or unfamiliar with the necessary steps, it is best to consult a professional mechanic for assistance.
Discuss the causes and fixes for P122B OBDII Code
Code P122B comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
