P0790 Code: Meaning, Symptoms, Causes & Fix

Overview

Symptoms

• reduced performance
• increased fuel use
• check engine light

Common causes

• Sensor drift or delayed actuation affecting normal/performance switch circuit malfunction
• Component out of calibration
• Connector pin damage/corrosion or harness stress near related components

How to diagnose P0790

1. Confirm P0790 and capture freeze-frame data with a professional scan tool.
2. Inspect wiring, connectors, and grounds related to normal/performance switch circuit malfunction for obvious defects.
3. Compare commanded vs actual values in live data under the same operating condition.
4. Check for related DTCs to identify the root-cause chain before replacing parts.
5. After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P0790

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with P0790?

Most vehicles can be driven short-term with P0790, but postpone heavy load/highway driving until repaired.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

1. Repair obvious wiring/connector faults first to prevent repeat parts replacement.
2. Address the root fault mode (performance) in the normal/performance switch circuit malfunction circuit/system.
3. Apply the required relearn/adaptation procedure if specified by service information.
4. Road-test and verify P0790 remains cleared under the conditions that originally set the code.

Fix options

• Test component operation against service specs.
• Clean/repair mechanical restriction where applicable.
• Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$200-$900

Common mistakes when diagnosing P0790

• Replacing parts without verifying voltage, ground, and signal integrity first.
• Ignoring related stored/pending codes that indicate upstream faults.
• Skipping post-repair verification drive cycle and readiness checks.

P0790 in common vehicles

P0790 appears across makes such as BMW, Mercedes-Benz, Audi, Volvo. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P0790?

P0790 is commonly set by performance faults affecting normal/performance switch circuit malfunction.

How much does it cost to fix P0790?

For P0790, repair costs are typically $200-$900 depending on exact root cause, labor rates, and part quality.

Can I clear P0790 without repair?

You can clear P0790 temporarily, but the code usually returns until the underlying fault is corrected.

Helpful tools

• Estimate repair cost
• Decode your VIN
• Calculate fuel cost