Transmission & Fuel System Diagnostic Codes Cluster (P0700–P0736)
An authoritative, technician-friendly hub for P07xx transmission and related fuel codes — now with detailed test values, step-by-step diagnostics, real cases and trusted references to aid fast, accurate repairs.
What this page is for (quick)
- Use this hub after you read codes — it groups codes by subsystem (sensors, switches, ratios, temperature).
- Follow the per-code test checklist: verify wiring/power → measure sensor resistance/voltage → compare live data → perform actuator tests → hydraulic checks if needed.
- Always confirm exact resistance/pressure specs in OEM TSBs or factory workshop manuals for the specific VIN.
Tools recommended: iCarsoft CR PRO S (full-system, adaptations, actuator tests), a quality multimeter, an IR thermometer for TFT checks, and a graphed live-data logger.
Index — Codes & links
- P0700 – Transmission Control System Range/Performance
- P0701 – Transmission Control Electrical Malfunction
- P0702 – Brake Switch Circuit Malfunction
- P0703 – Clutch Switch Circuit Malfunction
- P0704 – Transmission Range Sensor Circuit High
- P0708 – Transmission Fluid Temperature Sensor Malfunction
- P0710 – TFT Sensor Circuit Low
- P0712 – TFT Sensor Circuit High
- P0713 – TFT Sensor High Input
- P0714 – TFT Sensor Intermittent
- P0714 – Input/Turbine Speed Sensor Range/Performance
- P0716 – Input Speed Sensor / Correlation
- P0719 – Brake Switch B Circuit Low
- P0721 – Output Speed Sensor Range/Performance
- P0723 – Output Speed Sensor Intermittent
- P0723 – Gear 6 Incorrect Ratio
- P0729 – Incorrect Gear Ratio
- P0730 – Reverse Incorrect Ratio
- P0736 – Fuel Pressure Too High
Group: Core transmission faults (P0700 — start here)
P0700 — Transmission Control System Range/Performance
Definition: Generic code telling you the TCM has logged a transmission fault. Always read TCM-specific codes first.
Symptoms: Limp mode, MIL on, poor shifting. Typical search: “how to fix P0700 transmission limp mode”.
Step-by-step quick checks:
- Connect iCarsoft CR PRO S, read TCM stored codes (these point to the real cause).
- Capture freeze-frame data — note engine & transmission temps and vehicle speed.
- Check battery resting voltage (12.4–12.8V) and charging (13.8–14.6V). Voltage dips can create ghost codes.
- Scan for CAN bus errors and inspect TCM power/ground circuits.
Tip: many P0700s originate from a single failing solenoid or speed sensor — start with the lowest-numbered TCM code.
Group: Electrical / Switches (P0701–P0704, P0702–P0704 detail)
P0701 — Transmission Control Electrical Malfunction
Common causes: Solenoid coil open/short, connector corrosion, valve body harness damage.
Testing values & checks:
- Solenoid coil resistance: typical ≈ 10–30 Ω (varies by make) — consult OEM spec.
- Command solenoids via scanner actuator test (CR PRO S) and verify physical response (line pressure changes).
- Voltage on solenoid feed should be battery voltage (~12V) when commanded via driver (use backprobe).
P0702 — Brake Switch Circuit Malfunction (interlocks)
Why it matters: Brake switch informs TCM/ECM for shift interlock and torque management. Faulty switch may prevent shifting out of Park.
Tests: Live data brake-switch status toggle (0/1) while pressing pedal; multimeter continuity when pressed; verify 12V supply to switch.
P0703 — Clutch Switch Circuit Malfunction
Manual cars: test clutch switch continuity while depressing clutch. Confirm live-data toggle on scanner and check switch adjustment.
P0704 — Transmission Range Sensor Circuit High
What to check: TRS (neutral/PRNDL) voltage should change between ~0–5V as gear lever moves. A constant high (~>4.5V) suggests short-to-battery or misaligned sensor.
Group: Transmission Fluid Temperature (TFT) family (P0708, P0710, P0712, P0713, P0714)
The transmission fluid temperature sensor often uses an NTC thermistor. Wrong readings cause poor shift timing & limp mode.
| Code | Usual meaning | Quick electrical checks (approx.) |
|---|---|---|
| P0708 | General TFT malfunction | Live-data TFT vs coolant temp; sensor resistance at 20°C often 2k–20kΩ (varies) |
| P0710 | TFT Circuit Low (open) | Voltage ~0 V or sensor shows -40°C in scanner → open circuit |
| P0712/P0713 | TFT Circuit High / High Input | Voltage close to battery (~5V) → short to power; check harness near exhaust for melted wire |
| P0714 | TFT Intermittent | Wiggle harness while watching live TFT; intermittent spikes indicate wiring/connector fault |
Practical TFT test: With CR PRO S display TFT reading, place an IR thermometer on the transmission pan. Heat the trans (drive) and compare the two values — if TFT does not rise or jumps, inspect wiring and sensor resistance.
Group: Speed sensors & gear ratio codes (P0714, P0716, P0719, P0721, P0723, P0729, P0730)
Input / Turbine Speed Sensor (P0714 / P0716)
Symptoms: RPM surges, loss of torque management or slipping.
Common checks:
- Resistance: many variable reluctance (VR) input sensors ≈ 500–1500 Ω (approx); hall sensors are different — check OEM.
- Waveform: VR produces AC waveform; amplitude increases with speed — use scope or high-sample live-data logger.
- Physical: inspect sensor tip for metal debris/vibration wear.
Output Speed Sensor & Intermittent (P0719, P0721, P0723)
Symptoms: speedo dropouts, erratic shifting, limp mode. Long-tail phrase: “P0721 output speed sensor range performance fix”.
Quick test: Live-data compare input vs output speed while accelerating. If output freezes or spikes, suspect OSS or connector. Wiggle test the harness at the tail housing while watching live data to reproduce intermittent P0723.
Gear ratio codes (P0723, P0729, P0730)
These point to mechanical mismatch: worn clutch packs, slipping torque converter or incorrect final drive. Recommended: after excluding sensors & wiring, perform line-pressure tests and internal inspection.
Group: Cross-system — Fuel (P0736)
P0736 – Fuel Pressure Too High — added because fuel pressure anomalies affect torque management & can appear with transmission-related drivability faults.
Checks: fuel rail pressure measured with OEM gauge; inspect pressure regulator, return/bleed line restrictions; confirm with freeze-frame data when code set.
Practical diagnostics — full step-by-step (recommended order)
- Read & save codes (ECM + TCM) and note freeze frames (voltage, temp, speed).
- Electrical baseline: Battery resting (12.4–12.8V), cranking (≥9.6V typical minimum), charging (13.8–14.6V).
- Visual & connector check: Look for fluid in connectors, pin corrosion, heat-damaged insulation.
- Live-data capture: Input/Output speeds, TFT, solenoid states, line pressure, brake/clutch switch states.
- Actuator tests: Command solenoids via scanner — observe pressure and shift behavior.
- Resistance & continuity: Solenoid coils (~10–30Ω typical), VR sensors (~500–1500Ω typical) — OEM varies.
- Hydraulic checks: Line pressure tests under idle and load (use factory procedure; typical AT line pressures vary widely: ~2–20 bar depending on gear & vehicle).
- Repair + adapt: Fix wiring/replace sensors/valve body/TCM as needed, then clear codes and perform TCM adaptation/learn cycle (CR PRO S supports many adaptations).
Real-world mini case studies (representative)
Case A — P0721 (Output speed frozen) — Dodge pickup
Symptom: speedometer dropped to zero and truck shifted poorly. Diagnosis: live-data showed output speed frozen; connector found contaminated with ATF. Fix: clean connector, replace seal, clear codes. Result: immediate recovery; no sensor replacement needed.
Case B — P0713 (TFT high input) — Ford SUV
Symptom: false high temperature reading and limp mode. Diagnosis: TFT reading 300°F at cold start; discovered chafed harness shorted to +12V near exhaust. Fix: repair harness, replace sensor. Result: stable TFT readings and restored shift logic.
Case C — P0700 → P0755 (Shift solenoid B) — European sedan
Symptom: limp mode. Diagnosis: P0700 flagged; TCM stored P0755. Solenoid resistance out-of-spec. Fix: replace solenoid and clean valve body; perform TCM adaptation. Result: smooth shifting returned.
Common test values (reference table — approximate)
| Item | Typical Range (approx.) | Notes |
|---|---|---|
| Battery resting | 12.4–12.8 V | Below 12.2V suspect discharged battery |
| Charging voltage (running) | 13.8–14.6 V | Higher or lower requires charging system test |
| Solenoid coil resistance | ~10–30 Ω | Check OEM spec per solenoid |
| VR speed sensor resistance | ~500–1500 Ω | Hall sensors differ; check manufacturer |
| TFT sensor resistance (20°C) | ~2k–20k Ω | Manufacturer specific; thermistor curves differ |
| Line pressure (run/load) | ~2–20 bar (30–300 psi) | Value depends on gear & vehicle — use factory chart |
Always confirm values with the OEM workshop manual for the exact model/year — table is guide only.
Authority links & further reading
- OBD-Codes.com — canonical DTC definitions and common causes.
- AutoZone Repair Guides — OEM procedures and wiring diagrams for many vehicles.
- NHTSA — recalls / service bulletins that may affect transmission electronics.
- RepairPal — typical repair costs and diagnostic overviews.
- Factory service manuals & OEM TSBs — search manufacturer portals or dealer subscription services for model-specific data.
Including these citations helps search engines and AI Overview trust the technical content on this page.
Quick commands & live-data checklist (copy/paste)
# Live-data to capture (recommended): - BAT_VOLT: at rest, crank, running - INPUT_SPEED: idle and acceleration - OUTPUT_SPEED: compare with INPUT & wheel speed - TFT_TEMP: cold start, warm-up - SOLENOID_A/B/C: command ON/OFF, observe change - LINE_PRESSURE: idle & full-throttle test - BRAKE_SWITCH & CLUTCH_SWITCH: state change tests
FAQ — concise
Q: P0700 showed — do I replace the TCM?
A: Not immediately. Read the TCM stored codes — they usually identify whether the root cause is a sensor, solenoid, wiring, or mechanical. Replace TCM only after excluding wiring, power/ground, and software issues.
Q: Can low voltage cause P07xx codes?
A: Yes. Voltage instability during crank or charging can cause module errors and intermittent sensor faults. Always verify battery & alternator before deep-dive diagnostics.
Q: Will clearing codes fix the problem?
A: Clearing only removes the symptom temporarily. Always perform root-cause tests, fix the underlying issue, then clear codes and confirm with a road test and live data capture.
