P0791 moderate

Intermediate Shaft Speed Sensor A Circuit

The P0791 code means the vehicle's onboard diagnostic system has detected: Intermediate Shaft Speed Sensor A Circuit. This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: hard
Estimated cost: $150 - $1,200 (parts and labor)

Check Your Fluid First

ANCEL AD310 OBD-II Scanner

Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.

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Read Transmission Codes

LAUNCH CRP123X (Reads All Systems)

Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.

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Common Symptoms

Check Engine Light on
Intermediate shaft speed reading error
Shift quality degradation
Transmission may enter limp mode

Probable Causes (Ranked by Likelihood)

Failed intermediate shaft speed sensor A Very High
Contaminated or degraded transmission fluid High
Wiring or connector fault in the circuit Moderate
TCM internal circuit failure Low

Step-by-Step Diagnostic Procedure

Use a scan tool to monitor Intermediate Shaft Speed Sensor A data
Check transmission fluid level and condition
Inspect the transmission wiring harness and connector for damage or corrosion
Compare sensor readings to manufacturer specifications at various operating conditions

Frequently Asked Questions

What does P0791 indicate?

P0791 indicates a problem with the intermediate shaft speed sensor a circuit. This affects the transmission control module's ability to properly manage shift timing and quality.

Should I continue driving with this code?

You can drive short distances at reduced speeds, but the transmission may shift harshly or enter limp mode. Continued driving with transmission codes can lead to additional damage and more expensive repairs.

Is this an internal transmission problem?

Not necessarily. Many transmission codes are caused by external issues like wiring faults, sensor failures, or fluid condition. Proper diagnosis can often identify issues that can be repaired without opening the transmission.