OBD-II Fault Code

P1118: Manifold Absolute Temperature Circuit Low Input

Meaning, symptoms, likely causes, diagnostic checks and repair guidance for P1118.

System family

Powertrain

Manufacturer-specific

Repair category

Air / load sensor

Use this category to narrow your checks before replacing parts.

Severity

Medium

Severity is a general guide. Confirm with scan-tool data and vehicle symptoms.

What P1118 usually means

Manifold Absolute Temperature Circuit Low Input.

Common symptoms

Check Engine light; Poor drivability or reduced fuel economy depending on fault

Likely causes

Faulty MAP sensor; Vacuum hose leak/blockage; Wiring/connector fault; Low signal voltage; Weak power supply; High resistance/poor ground; Failed sensor

Diagnostic checks

Scan all modules and record freeze-frame data before clearing codes; Check battery voltage and related fuses; Compare MAP reading key-on-engine-off to barometric pressure; Inspect vacuum port/hose and wiring; Check sensor reference voltage, ground and signal voltage

Repair guidance

Clean blocked port, repair hose/wiring, replace sensor if confirmed faulty; Repair poor ground/power feed or replace confirmed faulty sensor

Verification after repair

Clear code, road-test through the same drive condition, then rescan

Note: Confirm vehicle make/model/year because manufacturer-specific codes can vary; Manufacturer-specific: confirm definition and test steps in the vehicle service manual. A DTC identifies a circuit or system condition, not always the failed part.