P1138 Audi Code - Long Term Fuel Trim Add. Fuel B2 System Too Lean
Quick Answer
P1138 Audi indicates Long Term Fuel Trim Add. Fuel B2 System Too Lean. Common causes include Intake air leak, Faulty O2 Sensor, Faulty Mass Air Flow (MAF) Sensor. 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
- P1138 Audi indicates Long Term Fuel Trim Add. Fuel B2 System Too Lean.
- Common causes
- Common causes include Intake air leak, Faulty O2 Sensor, Faulty Mass Air Flow (MAF) Sensor.
- 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 P1138 Audi Description
What are the Possible Causes of the DTC P1138 Audi?
- Intake air leak
- Faulty O2 Sensor
- Faulty Mass Air Flow (MAF) Sensor
- O2 Sensor harness is open or shorted
- O2 Sensor circuit poor electrical connection
How to Fix the DTC P1138 Audi?
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 P1138 Audi 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 P1138 Audi Code
1. What does the P1138 code mean on an Audi?
P1138 indicates that the long-term fuel trim for Bank 2 is too lean, meaning the engine is detecting too much air or not enough fuel in the air-fuel mixture.
2. What are the common symptoms of the P1138 code in Audi vehicles?
Symptoms may include poor engine performance, reduced fuel efficiency, rough idling, hesitation during acceleration, and the check engine light being illuminated.
3. What causes the P1138 code in an Audi?
Common causes include vacuum leaks, a faulty oxygen sensor, a malfunctioning mass air flow (MAF) sensor, fuel injector issues, or a failing fuel pump.
4. Can a dirty mass air flow (MAF) sensor trigger the P1138 code?
Yes, a dirty or faulty MAF sensor can misreport airflow data, causing the engine to run lean and triggering the P1138 code.
5. Is it safe to drive an Audi with the P1138 code?
While it may be possible to drive for a short distance, prolonged driving with a lean condition can damage the engine or catalytic converter, so immediate diagnosis and repair are recommended.
6. How can I diagnose the P1138 code on my Audi?
Start by checking for vacuum leaks, inspecting the oxygen sensors, cleaning or replacing the MAF sensor, and testing the fuel pressure to ensure proper fuel delivery.
7. Can a bad fuel injector cause the P1138 code?
Yes, a clogged or malfunctioning fuel injector can limit fuel delivery to Bank 2, resulting in a lean condition and triggering the code.
8. What tools are needed to fix the P1138 code?
Basic tools include an OBD-II scanner, a vacuum leak tester, a fuel pressure gauge, and possibly a multimeter for electrical testing.
9. How much does it cost to repair the P1138 code on an Audi?
The cost depends on the root cause. Replacing an oxygen sensor may cost $150-$300, while fixing vacuum leaks or cleaning the MAF sensor can be less expensive.
10. Can a clogged air filter cause the P1138 code?
While less common, a severely clogged air filter can restrict airflow, leading to incorrect fuel trim adjustments and potentially triggering the code.
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