Citroen 15cv P1629 Engine Trouble Code
What is Citroen 15cv P1629?
The Citroen 15cv P1629 check-engine light can indicate issues ranging from minor (loose gas cap) to serious (catalytic converter failure). Professional diagnostic scanning at a dealer or shop will identify the exact cause and required repairs.
P1629 on the Citroen 15cv
Owners of the Citroen 15cv should be aware that P1629 can appear alongside oil consumption warnings. Low oil pressure caused by a worn PCV system lets crankcase vapour contaminate the mass air flow sensor, sending erroneous readings to the ECU.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Citroen 15cv |
| Brand: | Citroen |
| Model: | 15cv |
| Code: | P1629 |
P1629 Citroen 15cv Symptoms
Check Engine Light
Illuminated Citroen 15cv dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Citroen 15cv
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Citroen 15cv
Increased Emissions
Failed emissions test due to P1629
P1629 Code Structure
Understanding what each digit means in the P1629 powertrain trouble code:
| P | 1 | 6 | 2 | 9 |
|---|---|---|---|---|
| Powertrain Code | Fuel And Air Metering | Fuel Temperature Sensor B Circuit Range/Performance | Turbocharger Boost Sensor A Circuit Low | Reverse Input Circuit |
How to Fix Citroen 15cv P1629
Diagnostic Steps:
Check if fuel pump primes when key is turned to ON. Measure fuel pressure and verify bright white-blue spark at all plugs. Also verify mechanical timing alignment.
Repair Solution:
Excessive air inflow may result from vacuum leaks, dirty sensors, or EGR valves not closing properly. Insufficient fuel can stem from dirty injectors, clogged filters, weak fuel pump, or leaking pressure regulator.
Technical Notes:
P1629 DTCs can be triggered by upstream issues. For example, a dirty MAF sensor may cause incorrect fuel-trim adjustments, leading oxygen sensors to report mixture problems. Address root causes first.
Citroen 15cv P1629 Repair Cost
MAF sensor replacement on the Citroen 15cv for a P1629 fault runs $220–$380 at a franchised dealer. OEM-equivalent aftermarket sensors are available for $80–$130 and are a reliable option for vehicles outside the factory warranty period.
P1629 Description
P1629 engine trouble code is related to Reverse Input Circuit.
Main Cause
The primary reason for P1629 OBD-II Engine Trouble Code is: Fuel Temperature Sensor B Circuit Range/Performance.
Common P1629 Misdiagnosis on the Citroen 15cv
On the Citroen 15cv, the EGR cooler is sometimes replaced for P1629 when the EGR valve position sensor is at fault. The two components share a fault pathway in older scan tools that do not display live EGR valve position data.
DIY Repair Guide: P1629 on Citroen 15cv
Battery terminal cleaning on the Citroen 15cv is a 5-minute job that resolves a surprising number of P1629 intermittents. Use a wire brush and a bicarbonate of soda solution to clean corrosion, then apply a thin coat of petroleum jelly to the terminals after refitting.
Preventing P1629 on the Citroen 15cv
For turbocharged Citroen 15cv models, allowing the engine to idle for 60–90 seconds before shutdown after hard driving reduces turbocharger heat soak and prevents the coking of oil that blocks VVT galleries — a known secondary trigger of P1629.
Frequently Asked Questions — Citroen 15cv P1629
A: Temporarily clearing P1629 can help determine whether it is intermittent or persistent, but it does not fix the underlying fault. The code will return if the problem is still present. Do not clear codes just before an emissions test without a proper drive cycle.