What Does P1106 Mean?
P1106 has a dual meaning depending on manufacturer: it can indicate a dual alternator lower output fault or a MAP sensor circuit producing intermittent high voltage. For MAP-related causes, the sensor signal sporadically spikes above normal range, causing momentary rich fueling conditions. For alternator-related causes, the lower output alternator in a dual-alternator system is not charging properly, potentially affecting electrical system stability.
Common Causes
30%
MAP sensor with intermittent internal failure causing voltage spikes
25%
Loose or corroded MAP sensor connector causing intermittent contact
20%
Dual alternator lower unit failing or belt slipping (if equipped)
15%
Chafed wiring in MAP sensor signal circuit causing intermittent short to voltage
10%
Vacuum leak at MAP sensor hose connection causing erratic readings
Diagnostic Steps
1
Step 1: Determine if the vehicle has a dual alternator system. If not, focus diagnosis on the MAP sensor circuit. If it does, check both alternator outputs with a voltmeter at the battery.
2
Step 2: Monitor MAP sensor voltage live data while tapping on the sensor and wiggling the connector. Watch for sudden voltage spikes that correlate with the intermittent fault.
3
Step 3: Inspect the MAP sensor connector for corrosion, spread terminals, or moisture intrusion. Clean contacts and apply dielectric grease.
4
Step 4: Check the MAP sensor signal wire for chafing, especially near hot exhaust components or sharp edges where the harness is routed.
5
Step 5: For dual alternator systems: inspect the lower alternator belt tension, wiring connections, and voltage regulator. Test output under load.
6
Step 6: If MAP sensor tests indicate intermittent failure, replace the sensor. Clear codes and road test to verify the intermittent condition is resolved.
Estimated Repair Cost
$60 - $400
Parts + labor, varies by vehicle and location
P1106 has a dual meaning depending on manufacturer: it can indicate a dual alternator lower output fault or a MAP sensor circuit producing intermittent high voltage. For MAP-related causes, the sensor signal sporadically spikes above normal range, causing momentary rich fueling conditions. For alter...
The most common cause of P1106 (Dual Alternator Lower Fault/ Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage) is: MAP sensor with intermittent internal failure causing voltage spikes
Typical repair costs for P1106 range from $60 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent MAP faults can cause momentary surging or hesitation. A dual alternator fault may lead to insufficient charging under heavy electrical loads, potentially causing system brownouts in commercial vehicles.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1106 to identify the root cause.
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Powertrain
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Engine Management / Charging System
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