Frequent breakdowns of my 2016 Tata Zest (P). Issue finally resolved?

The engine wiring harness was suspected to be the culprit. Part was ordered. This was replaced and technicians took the car for a long drive (>100km). Problem seems to be resolved for now.

BHPian srvm recently shared this with other enthusiasts.

I have been meaning to put a detailed post on the breakdown issues I have faced in my Zest (Petrol), XMS variant, 2016 make. It is a long read but if this helps anybody else out there, it will have served its purpose.

Since July-2022, I have been having intermittent problems in my car.

One of the two scenario happens: 

1. In slow moving, crawling traffic, the engine dies off. Immediate cranking does not help. Move over the car to the side of the road. Wait for 10-15 minutes. Sometimes, disconnecting the -ve terminal of the battery and waiting for 15-30 minutes helps. After all this, the car sometimes started again on cranking. Sometimes, it had to be towed away to service center.
2. Occasionally, during cold starts in the morning, the engine cranks with higher than usual revs (> 2500 rpm) and then slowly or immediately dies off.

Following is the timeline of the saga and the responses from Tata ASS on several occasions:

30th July 2022: Car stops on Old Madras road near TC Palya Gate on peak traffic. Pushed it to the side of the road. Disconnected the battery -ve terminal. Waited for 20 minutes. With good luck, it cranked and reached home with heart-in-mouth amidst heavy traffic.

31st July 2022: Tried cranking at my residential parking space. No luck. Even disconnecting and reconnecting battery did not help. No CEL or MIL indication in instrument display. Low oil pressure light was on.

2nd August 2022: Car was towed to Kropex Auto, Marathahalli. Odo was 61,200 km.

5th August 2022: TASS does error scan and tells me that Injector-4 problem showed up. They clear the errors. Replace 4 spark plugs. Vehicle delivered back to me saying that if problem persists then they might have to replace fuel injectors or ignition coil or both. Odo was 61231 km.

14-15th August 2022: Did a 500 km round trip. No problems except once while slowing down near a Toll plaza the engine died. Cracking again brought it back to life.

16th August 2022: Once again problem returned. Scenario-2 from above (cold start at home parking space). No CEL or MIL error. Only low oil pressure indication on instrument cluster.

18th August 2022: Starting problem persisted and I had kept battery disconnected. Technician from Kropex Marathahalli came home. Connected battery. Vehicle started when he cranked but was showing oxygen sensor error on error scanner.

19-26 August 2022: Problem persisted. Car started sometimes but I was never confident of taking it out in traffic.

27th August 2022: Car somehow taken to Kropex Marathahalli again. Odo was 62039 km. Fuel pump module changed (cost me Rs.11,000 approx). This was the 3rd fuel pump module. It was already changed once under warranty in 2018 by TASS (Urs Cars, Mysore). I asked them to change Timing belt, water pump, accesory belts as well.

5th September 2022: Car delivered to me by Kropex. Fuel leaked below the car everytime I tanked up. This was the time when petrol prices in Bangalore were approx. Rs.110 per liter.

5th November 2022: Car taken to Kropex to check this petrol leakage issue. They admitted that it was improper fixing of Fuel pump O-ring/gasket done 2 months earlier which was causing it. This was replaced and car delivered back to me. Odo was 64072 km.

Eight months of relatively peaceful ownership

25th June 2023: Car suddenly stops in moving traffic at Old Airport Road, Domlur. Odo was 71984 km. Sent family away by Uber. Disconnect and reconnected the battery again after 15 minutes. Car starts and I drive to Basavanagudi. Again car stops in moving traffic in Lalbagh road. Same 15 minutes battery exercise and it started again. Finally I reach destination at Basavanagudi & disconnect the battery. After 3 hours, battery reconnected, car does not start at all. I give up after several attempts including fuse checks.

Video taken next morning, 26th June 2023.

I swap the mini-relay for ignition with another similar specced relay in the engine bay fuse box. Voila! She fires up on first try and I drive directly to TASS Kropex Koramangala. I replace the faulty mini-relay with a new one. Problem resolved (for now).

11th July 2023: While driving in rush hour traffic on Nagavara flyover (near Manyata Tech park) the car abruptly switches off (Odo was 73038 km). Its raining and my dad's with me worried sick. No luck even after several attempts. Huge traffic pile up on the flyover because of my car. Even battery reconnect exercise doen't help. Fortunately, a flat-bed towing vehicle moving in the traffic sees my plight and loaded my car in the flat bed. I leave the car at Adishakti Motors (TASS), Hebbal around 8 pm.

12-15 July 2023: TASS does not find any errors in scan. Engine seems to fire normally. So, no corrective action. Paid around Rs.2000 for scan. On the way home, the engine died on Old Madras road at a traffic signal. Fortunately, it cranked again and I reached home. Now I was not confident of taking the car out in city traffic.

By end of July 2023, my dad gets admitted in hospital and I have no choice but to take the car out for several errands to hospital and back home.

4th August 2023: On the way home from hospital, the car stops again in dense city traffic at Vignana Nagar. Traffic piles up behind me in no time. Lots of abuses yet again. Somehow after multiple tries, car cranks and I gingerly drive home safely.

13th August 2023: It is raining and I'm driving home with my family. I stop at a pharmacy at Nagavarapalya near C V Raman Nagar to buy medicines. The car is idling for 2 minutes while I'm at pharmacy and before I come back it dies. No luck on repeated cranking. I open the hood and I sense that the engine bay is hotter than usual. But the coolant temp level in instrument cluster is normal. Now, I sense a pattern in the last few brakdowns. I wrap a wet towel on the coolant return pipe from engine for 15 minutes. Fortunately, the engine starts after the hose has cooled down. I drive back home gingerly without any more issues.

September 2023: Couple of more incidents, where engine dies but never in highway runs or when engine is cool. Only in crawling or slow-moving city traffic. I remove the coolant temperature sensor, clean it and put it back. Problem seemed to go away after this. 3 months of peaceful ownership.

16th December 2023: Vehicle stops abruptly at Silk Board junction around 9pm! (Odo was 76901 km) It was not crawling traffic until then. So engine was not really running hot. Only warm. Traffic piled up behind me in no time. By now, I'm an expert in removing battery terminals. Again, I quickly cover the coolant hose with a wet towel. 15 minutes pass - while my family curses me from inside the car and strangers hurl abuses at me from slow-moving car and trucks. Car starts after engine cools down and I reach my destination at Hulimavu without any further drama. Its beyond 9.30pm by then and traffic has thinned by Bangalore standards and engine doesnt really have chance to run hot. 

24th December 2023: I'm on my way from Bangalore to Chennai. There a traffic pile in the highway at Vellore due to a diversion. Car stops again abruptly while crawling slowly and refuses to start (Odo was 77335 km). Engine bay is very hot. Once again, a wet towel is wrapped coolant hose. Car starts after 10 minutes once engine cools down. I reach Kanchipuram bypass and stop for a comfort break (kid and elders in the car). Car refuses to start after the break. Engine is cool but still no luck. No CEL or MIL error on instrument cluster. Battery disconnected and reconnected after 15 minutes. Car starts, very rough idling, possibly misfiring for couple of minutes. Exhaust smell is pungent and not normal. I observe for 2 minutes while family is standing outside the car. I vary the rpm and check if engine dies. It does not. I ask my family to quickly get on board the car. I yell 'No more stops until we reach destination in Chennai'. Somehow, by God's grace we reach Chennai safely without further drama.

26th December 2023: Car taken to Lakshmi Tata, Ambattur, Chennai for checkup. SA took a lengthy test drive around Chennai along with me. No problems encountered even in traffic. We switched seats and I drove back to TASS. No issues. They also do diagnostic check. No errors found. Car returned back to me the same day. Odo was 77501 km.

27th December 2023: While doing cold start at home, engine died again. Here's a video.

After multiple attempts, it started again. I drove gingerly to Lakshmi Tata, Ambattur (about 15 kms away). On the way, the engine died at a traffic signal on MTH Road. Seeing the traffic pile up behind me, the kind-hearted traffic policeman pushed my vehicle past the signal and on to the side of the road. Once again, I wrapped a wet towel over the coolant hose and waited for 15 minutes. Car started after this and engine died again 100meters just before entrance of Lakshmi Tata service center. Same SA came and acknowledged the problem now since he also couldnt start the car. After repeated attempts, we could take the car inside TASS premises.

28th December 2023: TASS could not find any problems through fault scanner. They wanted to keep the car for 4-5 days to do a thorough check. They were still inundated with flood-affected cars due to Cyclone Michaung. I could not be in Chennai for that long since my home-base is Bangalore. For my peace of mind, I asked TASS to replace the coolant temperature sensor even though they were confident it wasn't faulty. (My thinking: Faulty coolant temp sensor is sending lower temperature data to ECU while actually the engine is running much hotter. And hence engine shutting down in peak, slow moving traffic even when only 3 bars are shown in insrument cluster. Max is 6 bars. However, this did not explain the occasional problems during cold starts). I took delivery of the car risking getting stranded on the way to Bangalore. Odo was 77544 km.

30th December 2023: I drove cautiously from Chennai to residence in Bangalore. Filled at Sriperumbudur COCO fuel bunk. Odo was 77599 km. No problems except while on KR Puram hanging bridge, I could feel loss of power in 3rd gear. A-pedal fully pushed in but car was struggling to maintain 30 kmph. Somehow crossed the infamous Tin factory traffic snarl and reached home safely. But I knew that there is some unresolved problems with the car.

20th January 2024: I had gone to Indiranagar. Car was parked for 3 hours or more. Cool engine. Odo was 77978 km. Car refused to start even after multiple attempts. Left car there on road side and took a cab home. 

21st January 2024 (Sunday): Came back and tried starting the car. Another video.

After half-hour of attempts, it started and I let it idle for few minutes. I gingerly took it to KHT Motors Service Center, Whitefield. Being a Sunday, it was closed. I informed the Security guard and left it there.

22nd January 2024: I went to KHT Motors Service Center (TASS) and explained the problems to Service Manager. Asked them to also do the annual service along with breakdown diagnosis. Fuel pump module was once again found to be the culprit. Fuel pump had to be ordered since it was not in stock. This is the 3rd replacement is less than 8 years, the last one lasted less than 18 months. I was not happy with its quality and lifespan. I informed the General Manager (Service) of KHT Motors and Regional Customer Service Manager of Tata Motors of my disappointment with the repeated failure of fuel pump and the turnaround time to replace it.

31st January 2024: Car was delivered to me after fuel pump replacement and annual service. Total bill Rs.19,222. I drove home in the evening traffic. I was 1 km from my home when the car again stopped in a narrow road. Traffic piled up in no time. After repeated attempts, the car started and reached home without further drama.

1st February 2024: In the morning, I try cold starting the car in my residential parking space. Vehicle refused to start even after multiple attempts. Odo was 78000 km. This is the video of my attempts at starting the car.

I call SA and SM at KHT Motors stating my situation and my dissatisfaction with their resolution. I take videos of the instrument cluster and share it with them as well as Tata Regional Customer Service Manager. KHT sends a technician home the same afternoon. He is also unsucessful in starting the car. His diagnosis: bad spark plugs and HT cables. He says he will return with them in few days time.

After several reminders, phone calls etc, KHT finally sends someone home on 7th February 2024. Senion Technician / Supervisor checked the spark plugs first. All 4 spark plugs found to be bad (these were about 18 months old). Replaced them with 4 new ones. Tried starting the car, and it still seemed to be misfiring. Now all 4 HT cables were replaced. Car started now but the idling was not smooth. The Supervisor drove the vehicle slowly to service center located 10 km away.

10th February 2024: I visit service center of KHT Motors to get an update. They inform me that during test drive, the engine seems to have died after about 20-25km of driving. Now they suspect the ignition coil. They place an order since it is not in stock. Again the waiting begins.

15th February 2024: I visit service center of KHT Motors to get an update. They have installed the new ignition coil. But the problem persists. Now I'm told that there is an error on scanning 'Fuel injector 4 is faulty'. Now they plan to remove the fuel tank and clean it. They also plan to clean the fuel lines, fuel filter etc. Again the waiting continues. I shoot an email to Tata Customer Care about my car and its frequent breakdown problems.

I received a standard reply from Tata Customer Care on 16th February with cc to KHT Motors Service Manager and Customer Care Manager (Tata Passenger Vehicles). This is followed by another email from CRM (KHT Motors) who assures assistance.

After frequent follow-ups, I'm informed on 21st February 2024 that in addition to all of the above, the Oxygen/Lambda sensor was changed and the problem is resolved. I go for a road test along with a TASS Mechanic. The car starts and drives well. We fill up about 10 litres of petrol and also do an emissions test which the car passes. I drive the car home. Odo is 78150 km.

On 23rd February morning, once again the car starts misfiring during morning cold start. And after rough idling for a minute, the engine dies. I again call up Technician from KHT Motors and inform him about the unresolved issue.

Technicians from KHT Motors (TASS) visit my home on 24th February. Engine misfires on starting, rough idling and slowly rpm dies to zero. Several attempts made with the same outcome. Some unburnt/half-burnt fuel is spewed through exhaust. Technicians now start doubting Throttle Body or ECU issues. They inform me that they will come back to check again on 2 days time. After they leave, I disconnect the negative terminal of the battery.

On Sunday morning (25th February), I reconnect the battery and try starting the car. The same misifiring issue persists for 3-4 attempts. On my final attempt, the car settles down to a stable 800 rpm idling. I wait for a while and the engine does not die. I slowly drive to TASS (9 km away) benefitting from the lean Sunday morning traffic. I park the vehicle at TASS and hand over the key to Security. I inform the Technician as well. I come home and shoot an email to Tata Cutomer Care with cc to KHT Motors as well. Once again I get a standard reply from Tata Customer Care on the same day. 

26th February: My car turned 8-year old on this day. But it is like a stranded whale. I still awaited developments / diagnosis from KHT Motors. 

2nd March: I visit KHT Motors after speaking with their CRM. In the past week, the technicians had taken the car for a lengthy road test. Car started and ran well. But on returning and idling the engine seems to have died again. I was informed that an error popped up on diagnostics indicating problem with throttle body. They have ordered that part and waiting for its arrival. Meanwhile, I requested CRM for a loaner car and they agreed. They gave me a Zest Diesel Automatic (XMA) with 52000km on the odo. I drove home in it. Atleast, I have a car now for local errands involving my aged parents. But I still wait for a proper resolution for my car's issues. Now it was 40 days since I first dropped her off at KHT motors. Of which she has been there for about 30 days.

12th March: My car was still at KHT Motors. Throttle body was replaced and checked. Problem is not resolved. I was informed the following: They took the car for a lengthy road test (>40kms). Car seems to have run ok but Engine malfunction light seems to have come on. I'm told that they are in touch with Tata Engineers on this. I continue to use their loaner car. But I'm permitted to use it only inside Bangalore city. I have asked them permission to take it to Bangalore airport (which is well outside the city) this week. They have agreed to it. Loaner car does not have Fastag. I will have to pay double fee in cash. Until I get my car back, no more out-station trips by car. 

23rd March: Now the engine wiring harness was suspected to be the culprit. Part was ordered. This was replaced and technicians took the car for a long drive (>100km). Problem seems to be resolved for now. Car delivered to me today. Odo was 78,400kms. KHT motors told me that they'll keep the job card open for a week, just in case something crops up. Cost of wiring harness plus labor ₹17,800. Gratitude to Mr Venkatesh (Technician), Ms Kavitha, Mr Karthik (both CRM) of KHT motors for patiently keeping me updated regularly.

June-2024: Odo stands at 81400km. I have driven 3000kms since taking delivery from service center in March. Since then I have not faced engine dying issues. However, there is still a wee-bit fluctuations in idling rpm, only occasionally, while waiting at traffic signal. It is more of a nuisance now. Not too bothered about it, as long as vehicle is running without getting us stranded.

Check out BHPian comments for more insights and information.