What Does P1111 Mean?
P1111 indicates either a dual alternator lower output fault or an intermittent high voltage condition on the MAP sensor circuit, depending on the vehicle manufacturer. The description is identical to P1106, suggesting a manufacturer-specific variant. The MAP interpretation points to sporadic voltage spikes on the MAP signal wire, while the alternator interpretation suggests the secondary alternator is underperforming or has an erratic output.
Common Causes
30%
Intermittent MAP sensor failure causing sporadic high voltage output
25%
Loose MAP sensor connector or damaged pins causing intermittent contact
18%
Dual alternator lower unit voltage regulator malfunction (if equipped)
17%
MAP sensor signal wire intermittently shorting to 5V reference or B+
10%
Vacuum supply hose to MAP sensor cracked, causing erratic pressure readings
Diagnostic Steps
1
Step 1: Determine vehicle application to identify whether this code relates to the MAP sensor or dual alternator. Check manufacturer-specific service information.
2
Step 2: For MAP-related diagnosis: monitor MAP sensor voltage with the engine running. Record data for several minutes to capture the intermittent high voltage condition.
3
Step 3: Wiggle the MAP sensor connector and harness while monitoring live data. Intermittent spikes during the wiggle test pinpoint a connection issue.
4
Step 4: Inspect the vacuum hose to the MAP sensor. A cracked or leaking hose causes barometric-level readings that register as high voltage.
5
Step 5: For dual alternator vehicles: measure the lower alternator output voltage under load. It should maintain 13.5–14.5V. Erratic output suggests a failing regulator.
Estimated Repair Cost
$60 - $450
Parts + labor, varies by vehicle and location
P1111 indicates either a dual alternator lower output fault or an intermittent high voltage condition on the MAP sensor circuit, depending on the vehicle manufacturer. The description is identical to P1106, suggesting a manufacturer-specific variant. The MAP interpretation points to sporadic voltage...
The most common cause of P1111 (Dual Alternator Lower Fault/ Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage) is: Intermittent MAP sensor failure causing sporadic high voltage output
Typical repair costs for P1111 range from $60 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent MAP faults can cause momentary fuel delivery errors leading to hesitation. Dual alternator faults in heavy-duty applications may affect critical auxiliary systems under high electrical demand.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1111 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Charging System
Difficulty
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