P1186 Code: Meaning, Symptoms, Causes & Fix

Overview

Symptoms

• hard starting
• engine may stall at idle
• hesitation under acceleration

Common causes

• High circuit resistance affecting fts low - fuel pump temperature sensor low
• Sensor output out of expected lower range
• Connector pin damage/corrosion or harness stress near related components

How to diagnose P1186

1. Confirm P1186 and capture freeze-frame data with a professional scan tool.
2. Inspect wiring, connectors, and grounds related to fts low - fuel pump temperature sensor low for obvious defects.
3. Compare live data against expected lower threshold and verify ground/reference circuits.
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 P1186

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

Can you drive with P1186?

Most vehicles can be driven short-term with P1186, 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 (low) in the fts low - fuel pump temperature sensor low circuit/system.
3. Apply the required relearn/adaptation procedure if specified by service information.
4. Road-test and verify P1186 remains cleared under the conditions that originally set the code.

Fix options

• Replace failed sensor if signal remains low.
• Verify ground path and signal integrity.
• Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$220-$1100

Common mistakes when diagnosing P1186

• 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.

P1186 in common vehicles

P1186 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 P1186?

P1186 is commonly set by low faults affecting fts low - fuel pump temperature sensor low.

How much does it cost to fix P1186?

For P1186, repair costs are typically $220-$1100 depending on exact root cause, labor rates, and part quality.

Can I clear P1186 without repair?

You can clear P1186 temporarily, but the code usually returns until the underlying fault is corrected.

Helpful tools

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