Code
P1135
FORD
P — Powertrain
Pedal Position Sensor A Circuit Intermittent
AI status
Completed
Completed
100%
Causes
- Faulty accelerator pedal position sensor (pedal module)
- Damaged, corroded or loose wiring or connector at the pedal sensor
- Intermittent short to battery or ground in the pedal sensor circuit
- Poor or intermittent VREF (reference 5V) or ground connection
- Water intrusion or corrosion in connector(s)
- Faulty ECM or intermittent input circuit in PCM
Symptoms
- MIL (Check Engine Light) illuminated
- Intermittent or delayed throttle response
- Reduced engine power or limp-home/limited-throttle mode
- Hesitation, surging or inconsistent acceleration
- Possible hard or inconsistent idle when fault occurs
What to check
- Scan for P1135 and other stored/pending codes; record freeze frame and PID data
- Monitor live accelerator pedal position PIDs (Sensor A and B) with scan tool while slowly pressing pedal
- With key ON (engine OFF) measure VREF (~5V) at pedal connector and verify good ground
- Backprobe sensor output (A) and look for smooth, monotonic voltage change from idle to WOT
- Wiggle/rock pedal harness and connectors while watching live data to reproduce the intermittent
- Visually inspect connectors for corrosion, bent pins, water ingress, or damaged insulation
Signal parameters
- VREF (reference) ≈ 5 V (present at sensor connector with key ON)
- Sensor A output: typically about 0.5–1.5 V at rest rising smoothly to ~3.5–4.5 V toward full pedal
- Sensor signal should change smoothly with pedal travel, no sudden jumps or dropouts >0.1 V
- No short to battery (signal stuck high) or short to ground (signal stuck low)
- Sensor output correlation: Sensor A should follow expected ramp and correlate with Sensor B if present
Diagnostic algorithm
- Retrieve codes, freeze frame and match occurrence to customer complaint. Note other related codes. 2) Visually inspect pedal module and connector for damage, corrosion and water. 3) With key ON (engine OFF) verify VREF (~5 V) and ground at pedal connector; repair any missing reference or ground. 4) Backprobe pedal sensor output (A) and observe live voltage while slowly operating pedal — expect smooth ramp without dropouts. 5) Wiggle the pedal harness, connector and related harness routing while monitoring PID for intermittent change; inspect for chafing points. 6) Check continuity between pedal sensor pins and ECM pins; check for shorts to battery or ground. 7) If intermittent and not reproducible, use a scope to capture transient events or perform a wiggle test while on road or during a test drive to reproduce the fault. 8) If wiring and connectors are good and sensor output is out of spec or unstable, replace pedal assembly/module. 9) After repair, clear codes and perform full functional test and test drive to confirm fault does not return. 10) If fault persists with good wiring and new sensor, consider ECM input circuit diagnosis/replacement by qualified technician.
Likely causes
- Broken or chafed wire between pedal sensor and ECM
- Corroded/loose connector pins at the pedal module or under‑dash harness
- Damaged pedal assembly or internal sensor fault
- Intermittent ground or VREF loss due to poor splice or connector
- Contamination (water/grease) inside pedal connector causing intermittent contact
Fault status
Status
Intermittent fault on Pedal Position Sensor A circuit detected by ECM. MIL set. May cause reduced throttle response or limp mode until repaired.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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