P1086: Tumble Generator Valve #2 LH Position Sensor Circuit Low Input

SUBARU BMW

Severity

Medium

System

Manufacturer-Specific Powertrain

Last reviewed: Jan 1, 0001 Last updated: Jan 1, 0001

Methodology: We combine code standards with complaint and reliability patterns, then review for clear, vehicle-first diagnosis steps.

Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).

Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.

What Does P1086 Mean?

P1086 is a manufacturer-specific diagnostic trouble code: Tumble Generator Valve #2 LH Position Sensor Circuit Low Input. This code applies to SUBARU, BMW vehicles. Unlike generic OBD-II codes, manufacturer-specific codes are defined by the vehicle maker and may only apply to certain makes and models.

Symptoms of P1086

⚠️ Check Engine Light (MIL) illuminated
⚠️ Tumble Generator Valve #2 LH Position Sensor reading at zero or minimum value
⚠️ Related system not functioning or in fail-safe mode
⚠️ Reduced engine performance

Common Causes

🔍 Open or broken wire in Tumble Generator Valve #2 LH Position Sensor circuit
🔍 Poor ground connection at Tumble Generator Valve #2 LH Position Sensor
🔍 Faulty Tumble Generator Valve #2 LH Position Sensor with no output signal
🔍 Disconnected or loose Tumble Generator Valve #2 LH Position Sensor connector
🔍 Blown fuse in related circuit

Frequently Asked Questions

What does P1086 mean?

P1086 indicates: Tumble Generator Valve #2 LH Position Sensor Circuit Low Input. The vehicle's computer has detected that the Tumble Generator Valve #2 LH Position Sensor is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1086?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1086 for extended periods may cause additional problems.

How much does it cost to fix P1086?

Repair costs for P1086 typically range from $20 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Repair broken wire or restore ground in Tumble Generator Valve #2 LH Position Sensor circuit
🔧 Clean and secure Tumble Generator Valve #2 LH Position Sensor connector and ground points
🔧 Replace failed Tumble Generator Valve #2 LH Position Sensor

1
Find your vehicle above
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

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