Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P1506/17914 - CTP Switch Does Not Open (Short To Ground)
1996 Audi A4 Base, StandardSECTION DTC P1506/17914 - CTP Switch Does Not Open (Short To Ground)
NOTE:
DTC is set when idle switch is closed for more than 3 seconds with throttle opening more than 7 degrees.
- Inspect Closed Throttle Position (CTP) switch connector for looseness and/or corrosion. CTS switch is located within Throttle Position (TP) sensor. Repair connector as necessary. If connector was not repaired, go to next step. If connector was repaired, erase DTC memory and test drive vehicle.
- With ignition off, remove air intake sound absorber. Disconnect TP sensor connector. Using a DVOM, check continuity between TP sensor terminals No. 4 and 6.
- Continuity should be present. Open throttle slightly. DVOM should show infinity (no continuity). If continuity readings are not as specified, adjust TP sensor. See CLOSED THROTTLE POSITION (CTP) SWITCH in ADJUSTMENTS article. After adjusting TP sensor, if continuity readings are as specified, go to step 5).
- If after adjusting TP sensor, continuity readings are not as specified, replace TP sensor. Erase DTC memory and test drive vehicle.
- Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
- Using DVOM, check resistance between TP sensor terminal No. 4 (ground) and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
- Using DVOM, check resistance between TP sensor terminal No. 6 (signal) and test box socket A4. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory and test drive vehicle.
- Replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and TEST DRIVE in this article. Recheck DTC memory and verify DTC does not set again. If DTC sets again, perform testing procedure again.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.