Renault Trafic 1.6 145392 Diff Pressure Sensor & 038096 Preheating Unit

for business enquiries email [email protected] www.orileysautos.com In this post, you will see how those faults were tracked, confirmed with live data, and fixed with a mix of hose repair, DPF cleaning, and glow plug replacement. Spotting the warning signs On start up, the van showed classic dashboard warnings you would expect with DPF and injection problems. The spanner light stayed on, and the message centre brought up check injection system. There can also be a check anti‑pollution system message on these when DPF issues are present. For quick reference, the main alerts were: * Spanner light on * Check injection system message Those warnings were enough to move straight to diagnostics. Plugging in the diagnostic tool Once the scan finished, three engine faults were stored. Two of them pointed us exactly where we needed to go. 1. 145392: Differential pressure sensor circuit * Relates to the DPF pressure sensor that measures pressure before and after the filter. 2. 038096: Preheating unit * Points to the glow plug preheating system, often meaning worn or failed glow plugs. Checking live data first Before turning any spanners, live data was checked. This is where you can confirm if the codes match what the engine is actually doing. The upstream turbo pressure reading should show a sharp rise and fall as you blip the throttle. Instead, the graph barely moved. There was a long delay and in places no change at all, which suggested either a faulty sensor or a problem with the pressure pipes. DPF pressure and soot readings were also treated with caution at this stage, because a dead sensor or broken pipe can give very misleading values. Signs of a blockage A flat or lazy pressure trace on the upstream pipe points to trouble. When the revs rise but the pressure line stays almost flat, you usually have either a blocked or split hose, or a failed sensor. Lifting the van for inspection Once under the van, attention went straight to the DPF. The differential pressure pipes sit on or near the DPF casing, running towards the sensor. Both tubes were visibly damaged and looked like they had been chewed or eaten through, likely by road debris or animals. Replacing the damaged hoses The old hoses were so weak they ripped as they were pulled off. New hose was cut to length, then fitted with clamps to secure everything. The basic steps were: 1. Remove the remains of the old pressure hoses. 2. Cut new hose to match the original routing. 3. Fit the new hoses and secure with clamps at each end. With the physical repair done, it was time to go back to diagnostics. Clearing faults and watching soot load On many Renaults, once a fault code is set for the DPF pressure sensor, the ECU stops updating pressure values until the code is cleared. That was the case here. The fault memory was cleared, then live data was checked again. Pressure values now responded, and attention turned to how blocked the DPF was. Holding the revs at roughly 1,200 to 1,500 rpm, the DPF pressure sat around 122 mbar, and the grams of soot shot up rapidly. The ECU would let this climb up to 62.5 g, which is the upper limit. Ideally, you want soot to be below 6 g, and anything under 10 g is acceptable on a healthy, regenerating system. With numbers like that at the start, the DPF clearly needed more than just a forced regen. Cleaning the DPF and replacing glow plugs Launch UK DPF cleaning fluid was then injected directly into the DPF through a suitable access point. The bottle was squeezed through until the cleaner was inside the filter, then the pressure in the applicator was released. The steps under the bonnet were: 1. Move the coolant reservoir for better access. 2. Remove the old glow plugs carefully. 3. Fit and tighten the new set of four plugs. With new hoses, fresh glow plugs, and cleaner in the DPF, it was time to let the system do its work. Monitoring the regeneration Back on live data, another fault check was done. No new codes appeared, so the engine was started and warmed. A short test drive of about a mile brought the temperatures up. At this point, DPF pressure at idle had already dropped to around 11 mbar, then settled nearer 7 mbar. When the revs were held, you could watch the grams of soot steadily falling on the graph. As pressure comes down into single figures, soot follows it. Once soot dropped below about 6 g, the DPF was back in a healthy range. The upstream turbo pressure pipe issue was left for another day, as the customer chose not to spend more while it was not yet logging its own fault. All done.